The Arab Agricultural Revolution and Its Diffusion, 700-1100 Author(S): Andrew M

Economic History Association

The Arab Agricultural Revolution and Its Diffusion, 700-1100 Author(s): Andrew M. Watson Source: The Journal of Economic History, Vol. 34, No. 1, The Tasks of Economic History (Mar., 1974), pp. 8-35 Published by: Cambridge University Press on behalf of the Economic History Association Stable URL: http://www.jstor.org/stable/2116954 . Accessed: 26/10/2011 17:14

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http://www.jstor.org The Arab AgriculturalRevolution and Its Diffusion,700-1100

THE rapidspread of Islam intothree continents in the seventh and eighthcenturies was followedby the diffusionof an equally remarkablebut less well documentedagricultural revolution. Orig- inatingmainly in India, where heat, moistureand available crops all favored its developmentand where it had been practiced for some centuriesbefore the rise of Islam, the new agriculturewas carriedby the Arabs or those theyconquered into lands which,because they were colder and drier,were much less hospitableto it and where it could be introducedonly with difficulty.It appeared firstin the easternreaches of the early-Islamicworld-in parts of Persia, Mesopotamia and perhaps Arabia Felix-which had close contactswith India and where a few componentsof the revolution were alreadyin place in the centurybefore the rise of Islam. By the end of the eleventh centuryit had been transmittedacross the length and breadth of the Islamic world and had altered, often radically, the economies of many regions: Transoxania, Persia, Mesopotamia,the Levant, Egypt, the Maghrib, Spain, Sicily, the savannah lands on eitherside of the Sahara, parts of West Africa and the coastlands of East Africa.It had very far-reachingconse- quences, affectingnot only agriculturalproduction and incomesbut also populationlevels, urban growth,the distributionof the labor force, linked industries,cooking and diet, clothing, and other spheresof lifetoo numerousand too elusive to be investigatedhere. This paper will firstdescribe the main featuresof the Arab agriculturalrevolution and then tryto explainits diffusion. In the courseof my research,which has been carriedon over a numberof years and in manyplaces, I have benefitedfrom innumerable kindnesses, great and small, whichwill be acknowledgedelsewhere. Here I should like to thankthose to whom my debt is especiallylarge: ProfessorsClaude Cahen, Pedro MartinezMontavez, Roland Porteres,Vivi Tackholmand JohnWilliams, and Drs. David Dixon, Hans Helbaek, Jean-JacquesHemardinquer and CarmelloTrasselli. I am also gratefulto ProfessorsC. A. Ashleyand Karl Helleinerand Dr. Roger Owen for commenting on draftsof this article.As this articleis a preliminaryreport on my research,the verynumerous primary and secondarysources used have not been cited. The reader who is interestedin the primarysources will findsome guidance in the Appendix. In my forthcomingbook, New Crops in the Early-IslamicWorld: A Studyin Diffu- sion,most of the pointsmade in this articleare developedin greaterdetail and full referencesare given.

S AgriculturalRevolution 9 I At thevery heart of therevolution were many new crops.Found by theArabs mainly in India,and in a fewcases in thelands of the conqueredSassanian Empire, which had receivedthem from India, the new cropswere introducedinto other, very different climatic regionswhere they played an importantpart in transformingcrop- pingpatterns. To mentiononly those plants whose progress we have been able to studyin detail-sixteenfood crops and one fibrecrop -the Arab conquestswere followedby the diffusionof rice,sorghum,hard wheat,sugar cane, cotton,watermelons, eggplants, spinach,artichokes, colocasia, sour oranges, lemons, limes, bananas, plantains,mangos and coconutpalms.1 With the exceptionof mangos and coconutpalms, which could be grownonly in tropicalcli- matesand thereforeappeared only in ArabiaFelix and along the coast of East Africa,the diffusionwas verywide: the new crops came to be grownin nearlythe whole of the early-Islamicworld and not a fewbecame, for smaller or largerregions, of greateco- nomicimportance. Thislist of new cropsis alreadylong and impressive,but it is far fromcomplete. It does not includeother food and fibrecrops diffusedin the same period,whose advancehas proveddifficult to tracein the sources.Nor does it includeplants known in thesere- gionsbefore the Arab conquests, new strains of which appeared and were diffusedin Islamictimes. It excludesplants and treesused principallyas sourcesof fodder,spices, condiments,medicines, drugs,cosmetics, perfumes, dyes, nuts and wood,as well as garden flowersand ornamentalplants. In the disseminationof all these kindsof crops,too, the early centuries of Islam saw greatprogress. And finally,the listomits a wholehost of unwantedweeds which were inadvertentlydiffused along withthe otherplants, some of whichwere later to provevaluable but aboutwhose inglorious his- toryalmost nothing is known.In short,a completelist of evenonly the usefulplants would be long indeed,numbering well into the hundreds.The achievementwas remarkable.It seemsall the more so whenwe rememberthat the diffusion of theseplants over a very large area was compressedinto the firstfour centuries of Islam; thatmost of the plants,being native to tropicalregions, were not

1 Separatechapters will be devotedto the studyof the diffusionof each of these crops in pre-Islamicand Islamic times in my forthcomingbook mentionedin the precedingfootnote. 10 Watson easy to growin the coolerand drierregions into which they were taken;that the plantshad revolutionaryeffects on the wholeagri- culturalsystem; and thatthe workof introducingand spreading thesecrops was done by-or at least underthe rule of-a people notcommonly thought to have greenthumbs. There had been little thatwas comparablein earlierhistory. The achievementwas not to be equalleduntil modem times, when the discovery of new con- tinentsallowed the exchangeof plant life betweenparts of the worldwhich had previouslyhad littleor no contact. Hand in handwith the new cropscame changes in farmingpractices.For one thing,a numberof thenew cropsled to the opening of a virtuallynew agriculturalseason. In the lands of the Middle East and Mediterraneanthe traditional growing season had always been winter,the cropsbeing sown around the timeof the autumn rainsand harvestedin the spring;in the summerthe land almost alwayslay fallow,usually even in irrigatedregions where at least someof thecrops available to theancients could, with special care, have givensatisfactory yields. Those cropsmentioned as summer cropsin theclassical Roman manuals-barley, trimestre wheat, ses- ame and variouslegumes-played a minorrole in someparts of the northernMediterranean, where the summerwas relativelycool, thougheven there they seem to havebeen littleused and werenot integratedinto any systematicrotation. But in the southernand easternparts of the Mediterraneanthey were practicallynever grown,at leastnot as summercrops. There the summer season was to all intentsand purposesdead. Since,however, many of the new cropsoriginated in tropicalregions of India, SoutheastAsia, and CentralAfrica, they could be grownonly in conditionsof great heat.In particular,rice, cotton, sugar cane, eggplants, watermelons, hard wheat and sorghumwere all summercrops in the Islamic world,though rice and hardwheat could also be wintercrops in certainvery warm areas. Several other important new cropswhich we havenot been able to studyin detail,such as indigoand henna, were also grownin summer.Through the introductionof summer cropson a widescale, therefore, the rhythm of theagricultural year was radicallyaltered as land and laborwhich had previouslylain idle weremade productive. Morethan this, the openingof a summerseason was one of sev- eralfactors-perhaps the principal one-permitting systems of rota- tionwhich made muchmore intensive use of theland. Whereasin AgriculturalRevolution 11 Roman, Byzantine and Jewishagricultural traditions, the normal practicewas to crop the groundonly once everytwo years,and under veryexceptional circumstances once everyyear, there appeared all over the Islamic world rotationsin which the land was cropped fourtimes or more,instead of once, in a twenty-fourmonth period. Thus winterwheat could be followedby summersorghum. As one travelerobserved in Cyprus,where the practicehad no doubt been introducedduring the Arab occupation,a summercrop of cotton could be just fittedin between two crops of winterwheat grownin successiveyears. In partsof the Yemen wheat yielded two harvests a year on the same land, as did rice in Iraq. Where plants with a shortergrowing season were used, such as spinach, colocasia or eggplants,the land could be cropped three or more times a year. The variationswere endless. Naturally,multiple cropping mined the fertilityof the land and could not be borne by every type of soil. But to combat exhaustionand even to improvesome soils, the Arab manualsrecommended extensive use of all kindsof animal and green manures,each with its special qualities and uses, as well as ashes,rags, marl, chalk and crushedbricks or tiles. They also urged much plowing,digging, hoeing and harrowingwhich, they stated, were to some extentsubstitutes for fertilizing and on occasion pre- ferable: accordingto al-Maqrlziland in Egyptwas plowed six times beforesugar was planted,while Ibn Bassal recommendedup to ten plowings-and manuring-beforecotton was sown. The new croppingpattern required much water, which in the lands of earlyIslam could be providedonly by artificialirrigation. In part,extra water was requiredsimply because the land was cropped more or less continuouslyand thereforecould not regain moisture duringthe long periodsof fallowingwhich had characterizedearlier agriculture.In part, too, water requirementswere greaterbecause the summercrops were grown at a time when-except in Arabia Felix-no rain fell. The new summercrops, mostly native to tropi- cal lands,were particularlydemanding of water.Sugar, for instance, when grown along the Nile, required not only the river's annual flooding-or the equivalent amount of water artificiallybrought to the land-but also twenty-eightheavy waterings after that; in Spain sugar was watered everyfour to eight days. Rice, accordingto Ibn Wahshiya,had to be grownon level land which was continuously covered with water fromplanting to harvest,though Ibn Luyiin said thatit could be grownif watered twice beforethe seed germi- 12 Watson nated and twiceweekly thereafter. Similarly, many of the other cropsrequired heavy waterings through much of theirgrowing season. Even thoseof the new cropswhich usually did not require artificialwatering-sorghum, hard wheat,watermelons and eggplants,for instance-gave much higher yields if watered at theright times.So, too,did thecrops of traditionalagriculture. But althoughmany of thelands overrun by theArabs (and parts ofthe Arabian peninsula itself) had knownextensive irrigation sys- temsin pre-Islamictimes, the irrigationworks to whichthe Arabs fell heir needed much improvementbefore the new agriculture could be introduced.One difficultywas thatby the middleof the seventhcentury many of theancient systems had falleninto decay. In Mesopotamia,for instance, the neglectof irrigationin the last halfcentury of Sassanianrule culminatedin a huge floodin the year629, which destroyed many embankments and works,includ- ingthe great Nimrud dam, and leftthe lower reaches of the Tigris a marshyquagmire. In ArabiaFelix, another large dam, that of Ma'rib, brokein thelater part of thesixth century, after which there is no evidencethat any Himyaritic irrigation works were in operation.In late-RomanNorth Africa and ByzantineEgypt, too, the area under irrigationshrank in thecenturies before the rise of Islam. And while we have no knowledgeof thefate of the irrigationworks of Spain duringthe rule of the Visigoths,one of the Arab conquerorsof Iberiawas reportedto say-wrongly,surely-that there was not a singlecanal in the country.A secondproblem was thatthe irrigationtechnology of the pre-Islamicworld was by and largeinade- quate for the new agriculture.With the exceptionof the Mesopotamiansystem, pre-Islamic irrigation consisted almost en- tirelyin the temporarytrapping of rainwater or riverfloods and the spreadingof themby gravityflow over the land. It therefore broughtwater mainly in one season,the time of rainsor floods,and could reach onlythose lands to whichgravity flow could be di- rected.Though efficient devices to overcomethese shortcomings ex- istedin thepre-Islamic world, they were in onlylimited use. With thislegacy of irrigation systems and technology,therefore, the new agriculturecould makelittle progress across the worldthe Arabs had conquered.Advances were easiest in partsof Persia and Upper Mesopotamia,where elements of a moresophisticated system were alreadyin place. Elsewherethey had to wait uponprogress in irrigation. AgriculturalRevolution 13 Thissoon came. Although deterioration may have continueddur- ing the earlyyears of Islam whileconquest proceeded and power was slowlyconsolidated, the periodfrom the earlyeighth century onwardssaw a sharpreversal. Old irrigationsystems were almost everywhererepaired and oftenextended. New ones werebuilt. At thesame time, the range of technologyfrom which irrigators could choose was greatlywidened by the spread throughthe Islamic worldof a profusionof devices,borrowed rather than invented by the Arabs,for catching,storing, channeling and liftingwater. Amongthe moreimportant of thesewere new kindsof dams,un- dergroundcanals (or qandt) which tapped groundwater and broughtit overlong distances, and a varietyof wheelsturned by animalor waterpower and used forlifting water-sometimes to greatheights-out of rivers,canals, wells and storagebasins. The resultwas to bringmuch more water to muchmore land: to irrigate landswhich in earliersystems were not, and oftencould nothave been reached,and to improvethe qualityof irrigation,that is to increasethe flow of water on manylands watered by moreprimitive techniquesin earliertimes. So greatindeed was theprogress made thatit would be onlya slightexaggeration to claim thatby the eleventhcentury there was hardlya river,stream, oasis, spring, knownaquifer or predictableflood that went unused. Many were fullyor almostfully exploited, though not always by irrigators,who had to competewith other users. The combinedeffect of all these advanceswas to createacross the Islamicworld a patchworkof heavilyirrigated areas, great and small,into which the new agriculturecould move,to transforman environmentfundamentally hostileto manyof the new cropsinto one in which,for a timeat least,they were grown with astonishing success. Butthe agricultural revolution was by no meansconfined to heavily irrigatedand fertileareas wheremultiple cropping on the In- dian model could be introduced.On the contrary,though the impactof the revolution was greatestin suchareas and thoughthey mayperhaps be regardedas thespearheads of agriculturaladvance, the new agricultureoverflowed their bounds to affectthe whole spectrumof land types-frombest to worst-thatthe early-Islamic peasanttilled. Virtually all categoriesof land came to be farmed moreintensively. In part,this spillover was made possibleby the factthat there was no sharpbreak between irrigated and unirri- gatedlands. Rather the various advances in irrigationhad endowed 14 Watson the early-Islamicworld with a gradationof artificiallywatered lands: at one end of it werethose which were under heavy, peren- nial irrigationand couldsupport the Indiansystem of cropping;in themiddle was a wide rangeof landswatered less heavilythrough theyear or foronly parts of theyear; and at theopposite end were landswatered only one or twicein a seasonthrough the capture, forinstance, of a flashflood or throughsparing use ofsmall amounts ofwater stored in a cistern.The possibilitieswhich partial irrigation openedup forintensifying land use werecompounded by the fact thatthe authorsof the Arabfarming manuals identified far more typesof soilsthan are mentionedby the ancients.By takinginto accountstructure, temperature and moistureof the soil,they were able to see muchmore clearly than their predecessors the potential ofeach soiltype. They assumed that all soilswould be used to their fullcapacity-even inferior and downrightbad lands,which the an- cientwriters did notdeign to consider. Furthermore,in devisingcropping patterns for lands on which themost intensive agriculture could not be introduced,early-Islamic landownersand peasantscould choose from a muchwider range of crops,the special requirementsof whichthey understood better thantheir predecessors. There were all the cropsof traditionalagriculture,the many new cropswhich were being diffused, and new strainsof old and new cropswhich, from the accountsof many writers,seem to have abounded.With this wider choice available theywere able to inventan almostinfinite variety of flexiblerota- tionswhich contrast sharply with the smallnumber of rigidrota- tionsof antiquity.These couldinvolve the elimination of fallowing in alternateyears, an irrigatedwinter crop followed by an unirri- gatedsummer crop or vice versa,the insertion of catchcrops (such as turnips,all kindsof legumes,and smallfruits and vegetables) betweenthe major crops, and thevarying of cropsover a periodof yearsso thatsix or eightdifferent crops might follow in succession on the same land,each chosenin the lightof whathad preceded and whatwas to comenext. By ingeniouscombinations which took fullaccount of the degree of watering available and thetype of soil, theywere able to cropalmost all categoriesof land moreheavily thanin thepast, and sometimesto achieveparticularly spectacular resultsby takingadvantage of local soil variationsand microci- mates.2

2 For severalof the ideas developedin this paragraphand the precedingone, I AgriculturalRevolution 15 Even on lands which in earliertimes had been thoughttoo dry, too hot, or too infertileto use, and which no artificialwatering could reach, the new agriculturemade importantadvances. Here again certain of the new crops were crucial. Though it required some moisturein the early part of its growingseason, sorghum,for instance,could maturein a summerthat was very hot and dry; it could also, as the Arab manuals pointedout, be grownon hard and sandy soils which other crops would findinhospitable, and could even help to reconstitutethese lands. Hard wheat could also endure much heat and drought.Though of less importance,watermelons, too, yielded satisfactoryreturns on lands once thoughttoo dry to use. These cropsthus allowed the marginof cultivationto be pushed back into the savannah or near-desertlands in which the Islamic world abounded-lands which previouslyhad been used only for sporadic grazingor had gone unused. Similarly,sugar cane, colocasia, coconutpalms and eggplantscould be grownon saltysoils, upon which cereals could not be grown,and helped to improve these. They thereforeencouraged an extensionof cultivationinto swamp lands lyingalong seacoasts and at the mouthsof rivers,into lands watered by slightlybrackish springs,and into lands which after centuriesof irrigationhad become too saline forother crops. Again, we learn fromIbn al-'Awwdmthat cottonwas grownon the worst lands of Spain and Sicily,and we may assume that this crop also helped to push back the frontiersof sedentaryagriculture. One of the directconsequences of the new agriculturewas higher and more stable agriculturalearnings. The total income generated by the agriculturalsector was higherbecause moreland was farmed, because more cultivated land was irrigated,because land was cropped more intensively,and because there was a wider variety of crops to choose from-some much more profitablethan anything available in earlier times. But the new agriculturealso helped to stabilize agriculturalincomes. No longerwas the rural community so dependenton a singleharvest, the size of whichwas at the mercy of an undependable climate. Instead an increasingnumber of producers could relyon two or more crops which maturedat different times of the year and whose exact time of maturation,in the case of irrigatedcrops, could to some extentbe controlledby regulating the flowof water. Moreover,with more land under irrigation,the damage inflictedby climaticfluctuations was greatlyreduced, since

am indebtedto the work of Dr. Lucie Bolens,whose publicationsare cited in the Appendixat the end of thisarticle. 16 Watson theflow of streamsand the outputof wellsvaried much less than rainfall;on thisaccount, too, the level of output-andhence earn- ings-variedless. The factthat hard wheat and sorghumcould be storedover very long periods allowed speculators and governments to build up surplusesin yearsof highproduction and low prices whichcould be releasedonto the market in yearswhen production was low and priceshigh. Because such activitiestended to keep suppliesof grainon themarket more nearly stable, they also helped to stabilizeprices and incomes,though occasionally the tacticsof unscrupulousspeculators and governmentshad the oppositeeffect. Morestable incomes were important not only in alleviatingthe pe- riodicmisery which punctuated the lives of ruraldwellers in earlier agriculturalsystems; they also made it easierfor peasants to meet theirobligations to landownersand to theState, and therebyhelped fora timeto keepintact a relativelyprosperous and freepeasantry and toprevent the excessive buildup of large estates. Bothcapital and laborcosts, however, were higher per land unit. More capitalwas requiredfor the constructionof irrigationworks and forthe levelingor terracingof land to be irrigated.In a less obviousbut perhapsimportant way, the new agricultureprobably also demandeda higherinvestment in tools,draft animals and out- buildings.Operating capital was also greateron accountof the largeramounts of seed, fertilizerand laborused on a givenland area in thecourse of a year.But thisincrease in capitaldid noton balancedisplace labor. On the contrary,though greater investment allowedcertain activities to be performedwith less labor,many op- erationswere added whichhad not been carriedout in earlierag- riculturalsystems and theresult was to increase,not reduce, labor requirementsper land unit.In fact,the new agriculturewas ex- tremelylabor-intensive. More laborwas requiredto construct,re- pairand operatethe irrigation works; to plant,care for and harvest cropson land thatwas morefrequently cropped; to tendto certain of thenew crops,such as sugar,which made much higher demands on labor than any of the cropsof traditionalagriculture; and to carryout the enormousamount of plowing,digging, hoeing and harrowing,as well as the extensivefertilizing, which were needed to maintainthe fertility of heavily cropped land. While some of the tasksof the new agriculturecame in what had been the dead or slackseasons of earliersystems, and could thereforebe performed by laborthat would otherwise have lain idle,more hands were un- doubtedlyneeded per land unit.This growinglabor-intensiveness AgriculturalRevolution 17 of agriculture,combined with the expansion of thetotal area under cultivation,created the need fora muchlarger agricultural labor force. Higherincomes per land unit, the availability of new land and the greaterdemands of the new agriculturefor labor probably all en- couragedearly marriageand large familiesand thus may have causedrural populations to grow.In anycase, whatever the explanation,there are signsfrom many parts of the early-Islamicworld thatthe countryside was becomingmore densely settled. Although no evidencehas survivedwhich allows us to documentthis phenom- enonin detail,we findthat in manyareas villages seem to havebeen largerand more numerousand that theyextended into regions whichin earlier(and oftenlater) timeswere not farmed.To give onlya fewexamples, some of whichsurely contain an elementof exaggeration,chroniclers or geographerstell that therewere 360 villagesin the Fayyum,each of whichcould provisionthe whole ofEgypt for a day;that there were 12,000 villages along the Guadal- quivir,which, if thiswas true,must have had littleagricultural land; thatthe coastbetween Tangiers and Melilla,which today is almostentirely abandoned, was denselysettled and prosperous;that on the road betweenGafsa and Feriana,a partof Tunisiawhich todayis desert,there were 200 villages;and thatalong the Tigris settlementwas continuous,so thatbefore dawn crowingcocks an- sweredone anotherfrom housetop to housetopall the way from Baghdadto Basra.Other kinds of evidencesupport the same thesis withslightly greater precision: an eighth-centurycensus of 10,000 villagesin Egyptshowed that no villagehad fewerthan 500 plows, whiledata fromthe seigneurieof Monrealein Sicilysuggest that somehundred years after the Normanconquest of the island-by whichtime depopulation may already have set in-the ruralareas of the seigneurie,amounting to some 1,000square kilometers, had about20,000 inhabitants. If in a fewareas, such as the Negev and theregion of thevilles mortes near Aleppo, settlement actually retreated,and in otherareas, such as the Diyala Plains,the evidence of growthis notclear, the overwhelmingweight of evidenceis on the side of heavygrowth of ruralpopulation. Almost everywhere frontierswere pushed back, empty spaces filled up, and settlement becamedenser and morecontinuous-all changes of greatsignifi- cancenot only for agriculture but also forthe development of trade, communicationsand centraladministration. Citieswere also growing:proof that, in spiteof denserrural pop- 18 Watson ulation,the countrysidecould exportan increasingsurplus of food- stuffs.Here again our informationis fragmentaryand usually un- satisfactory,but its combined weight supports the thesis of impressiveurban growth.To be sure, some coastal cities, such as Alexandria,Antioch and Carthage, declined as a more continental economywith an easternorientation appeared on the Africanand Levantine shores of the Mediterranean.But the old inland cities, such as Cordoba, Seville,Damascus and Aleppo, flourishedperhaps as neverbefore, and hundredsof virtuallynew cities,mostly inland, were foundedin almostevery part of the early-Islamicworld. Many became of great economicimportance. By contemporaryEuropean standards,not a few were enormous.Samarra, for instance,which was the capital of the Eastern Caliphate foronly a shorttime, was estimatedby Herzfeld,who excavated it, to have had a population of about a millionin 883; Baghdad was certainlylarger than Sa- marra. Cordoba, whose population in the tenth centuryLevi-Pro- vencal conservativelyestimated at 500,000, is now claimed by archeologiststo have contained about a million people. Although we cannotestimate the populationof Fatimid Cairo, nor any of the earlierfoundations out of which Cairo had grown,its greatarea and the apparentlyhigh densityof populationin parts of it speak for a verylarge city;so, too, do manyindications (of varyingreliability) in the textswhich tell of 100,000houses in the quarterof al-Qata'i' alone, of 400,000 soldierswho were billeted in the cityin the tenth century,of 50,000 donkeysto transportwares to and fromthe mar- ketsin the quarterof al-Fustdt,and so forth.Other greatcities there certainlywere, and a host of medium-sizedand smallertowns. All stood as witness to the agriculturaladvances of this world which was becomingmore populous and, quite possibly,more urbanized.

II Let us turnnow fromthe factsof this agriculturalrevolution and its diffusion-whichhave been difficultenough to establish-to the stillmore difficult questions of how and why thisdiffusion occurred. What particularconjuncture of factorsfavored the rapid transmission of new crops,farming techniques and irrigationtechnology at this particularpoint in time? Why did this revolutionnot occur earlier,or later?Why did it occur at all? Questionsof thiskind are not easy to answer. To explain is usu- AgriculturalRevolution 19 ally moredifficult-and more risky-than to describe.But in this particularcase the natureof the data availablemakes such an un- dertakingespecially perilous. The sources,which tell us muchabout the revolutionitself, say nothingabout the agentsof its transmission.Were theyroyal personages, many of whomwere knownto takean interestin farmingand botany,and to have collectedexotic plantsin botanicalgardens? Were they great landowners, who saw thecommercial possibilities that agricultural innovation opened up? Or were the unsungheroes simple peasants who in the courseof migratingwestward brought with them the crops and farmingtech- niquesthat they had knownin theEast? We cannotknow, though we may supposethat all threegroups were involved.Nor do the sourceshelp us muchto geta pictureof the structure and organiza- tion of the agriculturalworld into which these changeswere re- ceived. The kind of documentationwhich abounds for many countriesof medievalEurope-namely, the recordsof landed estates-has failedto survivefrom the early-Islamic world. We there- foredo not knowwhat the typical(or indeed any) agricultural undertakingwas like,and cannotbe surewhat features of agrarian organizationparticularly favored the diffusionof the agricultural revolution. Nevertheless,from the availablesources we can catch glimpses of a wide varietyof factorswhich seem to have facilitatedthe spreadof the revolution.So manyare these,and so diverse,that herewe can touchon onlya fewand mustdo so withutmost brev- ity. A Mediumof Diffusion To begin with,we shall argue that the early-Islamicworld broughtinto being a mediumwhich was peculiarlyreceptive to manykinds of noveltyand favoredtheir transmission. Many areas of lifewere affected by its propertiesof conduction,of whichagri- culturewas onlyone. The creationof thismedium began with the Muslimconquests, which led to the unitingof a largepart of the knownworld under one language,one religion,one legal system, and fora timeone rule.Many of theregions brought together had neverbefore been in directcontact; certainly the extremities of the Islamicworld in 1000 had neverbefore enjoyed such prolonged contactwith one another.The area unitedwas diversifiedas well as large,including a wide rangeof climaticzones and plantlife of 20 Watson verygreat variety. It was also strategicallylocated, with footholds on threecontinents; by reachingbeyond the frontiers of Islamstill fartherinto these continents, the early Muslims were able to make contactwith all the otherareas of the knownworld-areas which offered,among other things, a stillgreater variety of plantlife. In fact,partly because of theirstrategic location, throughout the Euro- pean MiddleAges the Arabs were the only people with what might be considereda reasonableknowledge of all threecontinents of the knownworld. Withinthe area of Arab dominion,and to some extentbeyond, therewas muchmovement of men,of goods,of technology,of in- formationand of ideas. Ibn Khaldfinwrote of the Arabsthat "all theircustomary activities lead to traveland movement,"and so it was to becomenot only of theArabs themselves, or thoseof Arabic stock,but also of the conqueredpeoples. The veryprocess of con- quest and settlementof new areas oftenled to considerablemove- mentsof peoples.Basra, for instance, and some of the new cities foundedin thesouth of Iraq, showa strangeamalgam of peoples: Yemenites,other Arabs, Persians, and Indiansall settledthere, and one maysuppose brought with them the techniques of farming and the cropsknown in theirhomelands. Muslim Spain was settledby Berbersfrom North Africa, as well as by immigrantsfrom Egypt, theYemen, Syria and stillfarther East. Trade,which it seemsbegan to flourishsoon after the Islamic conquests, gave riseto stillfurther movement,a movementwhich linked together all areas of the Is- lamicworld and evenareas lying beyond the outer reaches of Islam. The pilgrimageswhich Muslims made in greatnumbers, and par- ticularlythe pilgrimageto Mecca, broughttogether Muslims from distantcorners of theearth. Many pilgrims took advantage of their displacementto prolongtheir stay abroad, making visits to relatives in othercountries, studying in foreigncenters of learning,and just sightseeing.Political refugees, of whomas timewent on therewas an increasingnumber, account for still more movement. To these shouldbe added menof religionand scholars,both of whomtrav- eled widely;the authorsof Arab manualsof farming,books on botanyand pharmacopoeiaealmost all traveledextensively, many the lengthand breadthof the Islamicworld. But perhapsany at- temptto explainwhy people traveledin the Muslimworld is doomedto fail to accountfor the reallyextraordinary amount of comingand goingacross huge stretchesof land whichwe findall AgriculturalRevolution 21 throughthe Islamicsources from the period.All classesof people, it seems,were prone to thisrestlessness; all traveled-therich and thepoor, the scholar and theilliterate, the holy and thenot so holy. Povertywas no obstacle:one could moveby foot,begging along the way; relativescould be imposedupon endlessly;patrons were readilyfound for scholars or holymen, or thosewho posedas such; a place to bunk,and perhapsto eat,was availableoutside the main mosquein mostcities. Lured on in searchof money,adventure or truth,Muslims from every region left home and roamedto and fro over the continents,taking with them knowledge of the farming techniques,plant life and cookeryof theirhomeland, and seeingon theirway theagricultural practices, plants and foodsof new lands. In theirtravels the Muslimsof theearly centuries of Islamwere on thelookout for whatever could be learned.This was an attitude of mindthat went back to earliestdays of Islam.Perhaps because theArabs came out of an area whichwas a cultural,and sometimes an actualdesert, and overranareas of highand ancientcivilization, theywere fromthe beginningaware of theirintellectual and ma- terialdeficiencies, immensely receptive to the new,eager to learn fromthose who could teach,avid to ape the fashionsof the great centers.Into the taskof assimilatingthe materialand intellectual cultureof the ages theythrew themselves with all the enthusiasm of the nouveauriche. At the courtof the earlyAbbasid Caliphs in Baghdad,for instance, manuscripts from all over the worldwere collected,and as thesecould be read onlyby scholars,the transla- tionof books from Greek, Persian, Syriac and Sanskritwas actively promotedfor over a century.Among the booksso translatedwere manyworks on agriculture,botany and pharmacology,all of which helpedto makeArabs familiar with plants they had notseen. Much laborwas spentin identifyingthese plants, and someof the early lexicographicalworks are devotedsolely or partlyto thisproblem. Similarly,in Spain,the Far Westof the Easternworld, and during the earlycenturies of Islamicrule a backwater,the buyingof culturewas pursuedwith a vengeance.There the Umayyadrulers sparedno effortin attractingscholars from centers of learningand buildingup libraries.Although almost all of the SpanishUmayyad rulerswere active in bringingculture to theirpeople, the workof al-Mustansirwas perhapsexceptional: he sentagents to Baghdad, Damascus,Cairo and othercenters to purchasewhatever valuable bookscould be found.The ImperialLibrary contained, according 22 Watson to one source,400,000 volumes. The listingof thesebooks filled 44 indexcatalogues of 20 folioseach. The latestbooks were said to be availablein the Libraryalmost before anyone had read the books in theEast. Translators,copiers, bookbinders were legion. As faras materialculture was concerned,the Arabs in theirtravels showedthe same eagernessto reachout and acquirewhatever was to be had fromthe far corners of the earth,and Arabsbecame perhapsthe greatest collectors of all times,building up hugecollec- tionsof rare and exoticobjects. Not onlyrulers and theircourts, but otherprosperous people set aboutcollecting in the grandman- nerwhatever took their fancy, or whateverthey thought might im- press:rare birds, wild animals, beautiful slaves, jewels, coins, plates, rugs,plants and, as we haveseen, books-all fromall overthe world. An unkindsoul might go on to pointout thatthe books themselves werein manycases littlemore than collections-collections of for- eignor obsoletewords, of odd facts,of namesof plants,medicines or places,or of sayings,writings and judgments,and so on-with littlein theway of theory or interpretation. The modemreader may findsuch books indigestiblebut they delightedthe mind that soughtto possess, enjoy and doubtlessto showoff all thegood things theworld had to offer. In the mediumwhich was being thus createdin the worldof earlyIslam there were many directions of flow, for in thisessentially syncreticcivilization whatever could be usefullyassimilated was snappedup and diffused.But one channelwas of overridingimpor- tance: it began at the easternextremity of the Caliphate,in India and Persia,and traversedthe entire breadth of theIslamic world up to Moroccoand Spain.The easternprovinces early became the gate- wayfor the entry of Indianand Persianculture which was eagerly soughtafter there and fartherto the West.This movementwest- wardswas intensifiedwith the rise of theAbbasid dynasty at Bagh- dad in the middleof the eighthcentury; these rulersand their courtsconsciously imitated Indian and Persiancustoms, and they in turnwere imitated by a wholeseries of courtswhich sprang up fartherto the West-in Egypt,Tunisia, Morocco and Spain. Over thiseast-west route moved not onlymost of the new crops,the farmingpractices and theirrigation technology that were the main componentsof the agriculturalrevolution, but muchelse thatwas to shape the worldof classicalIslam: higherlearning, industrial technology,fashions of dress,art forms, architecture, music, dance, AgriculturalRevolution 23 culinaryarts, etiquette, games and so forth.The end resultof so muchdiffusion through this medium was at once to strengthenthe unity,begun by theconquests, of thisvast world and to set it apart fromboth its predecessors and itsneighbors. There emerged a civil- izationwith a lookof newnessfashioned out of elementsthat, for themost part, were old. The Pull ofDemand But a mediumof diffusion,however great its receptivityand its powersof conduction, was notenough. For thenew crops,and with themthe agricultural revolution, to be disseminatedon a wide scale and to become of great economicimportance, much more was needed.On theone hand,there had to be a substantialdemand for the new cropsas foodstuffsor, in the case of cotton,as a textile fibre-a demandwhich had to be createdsince the crops were new. Andon theother hand, producers had to be able and willingto supply the cropsat priceswhich would permitsupply and demand curvesto intersectat levels of productionthat were significant. These conditionswere satisfied, it seems,by the actionof a num- ber of factors,some of whichserved to createa growingdemand and othersof which helped to facilitatesupply. They were at work in everypart of the Islamicworld. Together, they constituted the economicframework in whichthe carriersof the agriculturalrevo- lutioncould successfully operate. One couldof course argue that demand is nota problem:supply will createits own demand.Once a planthad been introducedas an oddity,perhaps in a royalgarden or in a peasant'splot, its pos- sibilitieswould be seenby a fewwho would start to use it,and as a matterof coursedemand would grow. It is possiblethat for a few of the new plantsthis explanation is correct.But in the mainwe do notbelieve that the process was so simple,that what was in fact a radicalchange in dietand in habitsof dresscould occur so easily. The evidencesuggests that the processof enlargingdemand was morecomplex, more deserving of study. In fact,many of thenew cropsthat were at the coreof the agriculturalrevolution were first known to the Islamicworld as medicines.Many of themindeed had been describedby Theophrastus (d. c. 285 B.C.) in hisEnquiry into Plants, by Dioscorides(fl. 1st c. A.D.) in his Materiamedical, or in otherclassical books of simples; and smallquantities of sugarand rice,for instance, were imported 24 Watson intothe ancient Mediterranean as medicinesbut not,it is believed, grownthere. Through the Arabic translation of Dioscoridesand of otherGreek, Roman and Indianworks of medicineand pharmacy, as well as throughoriginal works on pharmacywhich began ap- pearingin Arabicby theninth century, the inhabitants of theearly- Islamicworld were made aware of thealleged medicinal properties of manyexotic plants. We may assumethat some of thesewere importedand sold at highprices as medicines,though nothing is knownabout this trade until a laterperiod. It is also possiblethat thissmall market for some of the new plantsencouraged import substitution,and thatin thisway someof themcame to be grown in partsof the Islamic world to supplya demandfor remedies. How- ever,we thinkthis unlikely. The marketfor exotic cures must at all timeshave been smalland composedlargely of wealthyfaddists willingto pay highprices. By itselfit would probablynot have stimulatedany significantamount of importsubstitution, particu- larlyas theseexotic plants were difficultto growin the Islamic world. The nextstep in the enlargementof demandwas thereforeits transformation:instead of beingthought of mainly,or exclusively, as medicines,the new plants came to be demandedas foodstuffsor, in thecase of cotton,as a textilefibre. This mayhave come about in severalways. In veryearly times the migrationof Indiansand Persiansinto parts of Iraq musthave beenimportant in introducing new tastes;in slightlylater times, when the new tasteshad become moregeneral in the East, the movementof easternersto settlein the morewesterly parts of Dar al-Islammust have carriednew modesof eating and dressingfarther and fartherwestwards. Travel mustalso haveplayed a part,allowing westerners to see,try, imitate and bringhome the customsof the greatcenters of fashionin the East. But we believethat in the spreadingof new tastesa crucial rolewas playedby theuppermost classes of early-Islamicsociety- the rulers,their courts, and othervery wealthy people in the cap- italsand in provincialcenters. The Arabhistorians and chroniclers tell of greatfeasts offered by the easterncaliphs in whichno ex- pense was sparedto regale guestswith exoticdishes, sometimes made withingredients brought from afar. Many-perhaps most- of thenew plateswere of Indianor Persianorigin, and not a few used one or moreof our plants.The caliphs,who had been aping theSassanians and Indians,were in turnaped by theircourts, and AgriculturalRevolution 25 thecourts by thelarge class of wealthylandowners, administrators and merchantswho lived in the early-Islamiccapitals and great provincialcities. These were thenfollowed to varyingdegrees by peoplefarther and fartherdown the social scale. All the whilede- mandfor exotic produce grew. The eagernessof early Muslims of diverse ranks to copythe mores of thosethey regarded as theirbetters served to enlargedemand notonly vertically-that is to say,down the social ladder-but also horizontally,over space. For the easterncourts of the Umayyads and Abbasids,which were imitating still more easterly courts, were themselvesimitated, as the Muslimworld fragmented into a num- ber ofpolitical entities, by new courtsthat sprang up in the West: in Egypt,Tunisia, Morocco and Spain. In Spain diffusionwas ac- celeratedby thecollapse of theSpanish Umayyad dynasty and the appearanceof a largenumber of pettykingdoms, each withits own court;the new Spanishcourts imitated one anotheras well as those of theEast. In short,the tastefor exotic foods and modesof dress spreadover space as one courtcopied another, and thenbroadened as it moveddown the socialpyramid. At somepoint demand in a particularregion became greatenough to justifyimport substitution.Local sourcesof supplydeveloped. Though these may have been expensiveat first,they probably cheapened as skillswere ac- quiredand thescale ofproduction increased. With lower prices the marketno doubtwidened still further. Occasionallythe texts afford us glimpsesof stagesin thisprocess. In the treatiseof the tenth-centurygeographer, Ibn Hauqal, we learnof a landowner,an Emirof Mosul,who seized the rightmo- ment,after demand had become greatenough, to startgrowing some of the new cropson his own land. We are told thathe in- tendedto planthis lands with cotton and riceand expectedthereby to doublehis revenues. The processmust have worked in muchthe sameway elsewhere,being repeated time and againin one partof the Islamicworld after another, making available what had been costlyimported foods to a widermarket of people. By thethirteenth century,when a few cookbookswere writtenthat have survived, thenew foodsseem to be commonplace,at leastin thekitchens of thesefor whom the bookswere written-inseveral cases, admit- tedly,well-to-do people. Virtuallyall the cropsare mentionedin thesebooks. For mostthere are manyrecipes: there were dozens of differentways of preparingeggplants; sugar had become the 26 Watson mainsweetening; the juice and fleshof sour orangesand lemons werewidely used in preparingmeats, fish, poultry and desserts;the uses of ricewere legion; so werethose of hardwheat. The process thusseems to havebeen carriedto its conclusionby the timethese bookswere written. Indeed sincesome of the dishesdescribed in the recipebooks were mentionedin muchearlier texts, and were probablymade in the same way in earliertimes, the books may reflecta statein the culinaryarts-and hencea broadeningof demand-thathad beenreached some centuries before. Somethingof thesame process may be seen in the movementof cottonacross the Islamicworld. The firstcotton or partiallycotton clothsfound in Egyptappear to be of Persianmanufacture, doubt- less importedby therich who wereadopting foreign fashions, perhaps not onlyin dressbut in interiordecoration. Partially cotton clothsof slightlylater manufacture, dating from the eighthand ninthcenturies, were probablyactually made in Egypt,but still imitatedPersian designs and may stillhave used raw cottonim- portedfrom the East. By the tenthcentury a good deal of cotton was probablygrown in Egyptto cope withthe increasing demand, thougheven theneastern designs were stillbeing used. In West Africa,in the twelfthcentury, we catch anotherglimpse of a stage in the changingof taste: Al-Idrisli,writing of the townsof Silla and Takrir,relates that "the rich wear clothesof cotton;the commonpeople dress in wool." This single sentence, seemingly trivial, speaksworlds to thosewho have earsto hearits message.It shows wealthyWest Africanscopying what had becomethe mannerof dressof manyEgyptians, who in turnhad copied the Easterners. We do notknow when cotton growing was introducedinto this re- gionwhere today cotton is an importantcrop and theprincipal fibre fromwhich clothes are made,but we maysuppose that it was some timeafter the fashionset by the richwas sufficientlywidespread, and hence the demandfor cotton great enough, to induce some farmersto experimentwith its cultivation.In muchthe same way, cottonmust have movedfrom Egypt farther west, across the north ofAfrica into Spain and fromone Mediterraneanisland to another. FacilitatingSupply But an increasein demandcould not by itselfbring about diffusion if therewere obstacleswhich made the introductionof new cropstoo costly,which prevented supply and demandcurves from AgriculturalRevolution 27 intersecting.We shall arguethat the centuriesfollowing the Arab conquestssaw manychanges in thecountryside of the Islamic world whichon balance facilitatedsupply or-to put it anotherway- movedsupply curves downwards. One suchchange has alreadybeen noted:the advances in irrigation.Without improvements in the extent and qualityof irrigation, thenew agriculturecould not, as we have seen,have been diffused on a significantscale. It is thereforeimportant to searchfor the agentsresponsible for initiating and administeringirrigation proj- ects,as well as theframework of institutionswhich allowed or en- couragedthem to operate.A leadingrole was playedby the State. Not onlydid it financethe repair of someof the large-scaleirriga- tionschemes of pre-Islamictimes which had falleninto ruin, but it also undertooknew schemes,which substantially added to the irrigationinfrastructure of the early-Islamicworld. These ranged fromthe construction ofdams, reservoir systems and canal networks affectinglong stretches of greatriver valleys to muchsmaller proj- ectswhich brought water to thelands of a singlevillage. The State was also responsiblefor the administrationof manyof the larger irrigationworks, which in Iraq,for instance, employed several thou- sand functionariesand manylaborers. Of course,not all rulersor theirsubordinates cared equallyabout the operationof irrigation systemsor thewelfare of thecommunities that depended on them. Withalmost monotonous regularity, periods of large-scaleinvest- mentand carefulcontrol were followed by periodsof neglectand maladministration.On balance,however, the contributionof early- Islamicrulers to the developmentof irrigationseems to have been a stronglypositive one, accounting for a largemeasure of what was achieved. However,for medium-sized and smallerprojects the initiative was oftenprivate, coming from wealthy landowners, prosperous peasant-proprietors,communities of irrigators or would-beirrigators, andassociations of these communities. Even here the State must have playeda fundamentalpart in providingthe securityneeded to per- suade othersto invest.But in stimulatingprivate initiatives certain partsof Islamiclaw seem to have been veryimportant. For these the rulersand theirsubordinates were not primarilyresponsible (thoughthey played a partin theirenforcement), since in classical Islamlaw was forthe most part not legislated or decreedbut rather derivedfrom the Koran, from the alleged doings and sayingsof the 28 Watson Prophet,from later attempts to extendthe principlesthought to underliethese, and forareas whichthese did not coverfrom cus- tomor consensus (ijmd'). The Prophethimself had said muchabout rightsto waterand had settledmany irrigation quarrels, and from hissayings and rulings,worked over by laterjurists, there emerged a substantialcorpus of irrigationlaw whichclearly established the rightsof the partiesinvolved in all mannerof disputes.Although thislaw did not alwayswork towards the optimumeconomic use of land and water(for instance, in all but the Hanafitelegal tradi- tionland and waterrights could not be disposedof separately),it was a distinctimprovement over the water law of pre-Islamictimes ofmany of theregions affected; in muchof pre-IslamicArabia, for instance,water rights were usuallyestablished and transferredby force,and in manyparts whole tribesexercised collective rights overwells. By enshriningindividual rights and spellingthese out in detail,Islamic law undoubtedlyencouraged private investors. Otherprovisions of Islamiclaw workedin otherways to encour- age investmentin irrigationor to encouragethe new agriculture moredirectly. The laws concerningtaxation are hereof specialin- terest.One law providedthat land wateredby buckets(or in later extensionsof thisprinciple, land thatwas wateredby waterwheels or any otherkind of liftingdevice) shouldpay onlyone-twentieth ofits produce in taxinstead of thenormal tenth or anyhigher rate thatmight have applied.This provisionsurely must have givena strongincentive to introducethe water-liftingdevices which be- cameso commonin theIslamic world, and whichwere crucial both in prolongingthe irrigationseason afterthe annualflooding of a riverand in bringingwater to landsthat could not be reachedat all by gravityflow. Another law exemptedor taxed at onlyhalf the normalrate lands planted with permanent crops which had notyet begunto yield.This no doubtencouraged investment in treecrops, such as bananas,citrus, mangos and coconutpalms, which ulti- matelyyielded far higherreturns than the traditionalcrops. An- other importantprovision of Islamic law was the ruling of Muhammadthat the person who broughtinto cultivation land that had been "dead"or uncultivatedfor more than three years should gainoutright ownership of thisland; moreover,such land, when it began to produce,was to be taxedonly one tenthof its produce and notat anyhigher rate which was otherwiseallowable. This law appearsto haveapplied to tribalpasture lands as well as completely AgriculturalRevolution 29 abandonedland; it may thereforehave been a powerfulforce fa- voringthe expansionof sedentaryagriculture over grazing,and in pushingback the frontierof settlementinto the desert.More gen- erally,the laws of taxationspelled out whattaxes were to be paid by differentcategories of land and differentkinds of crops,and comparedto whatwent before or came laterthese taxes seem to have been relativelylow. The landowneror tenantwho introduced new techniquesor new cropswhich promised higher returns was thereforereasonably well assured that a substantialpart of the gains of his innovationwould be his. At least in the earlycenturies of Islam,they could not easilybe scoopedoff by capricioustax col- lectorsor by a greedystate. Althoughthe records of landedestates in theearly-Islamic world have not survivedand we thereforehave littleinformation about agriculturalorganization, it does seem that some landholdingar- rangementsalso favoredinnovation. At thetime of theIslamic conquests the large estates,which almost everywhere had come to dominateand oftento monopolizeagriculture, were oftenbroken intosmaller proprietorships which could be operatedby an owner and his familyassisted perhaps by a few paid workers.Large es- tatesremained, of course, and newones were built up, butfor some centuriesthe largeestate had to competewith an alternativeform of landholdingin the shape of largerand smallerpeasant proprietorships.Competition was intensifiedby the existenceof much smaller,heavily irrigated "garden" areas in the immediatehinter- land ofnearly all themajor cities and elsewhere,on whichmany of thenew cropswere also grownand thenew techniquesof farming applied.These wereprobably both owner-operated and tenant-operated.The existence,therefore, of threevery different forms of ag- riculturalundertaking, and the inevitablecompetition between them,probably was importantin stimulatinginnovation by landownersand tenantsalike. The largerestates, moreover, seem to havebeen relativelyfree of the retrogradefeatures which kept productivity low and discour- aged innovationon the estatesof late Rome,of Byzantiumand of medievalEurope. For example,the early-Islamicestate does not seemto have had a demesne,in the senseof an importantpart of theestate which the owner operated for his own profit with the help of involuntarytenant labor. Holdingsof both ownersand their tenantsseem to have consisted of consolidated blocks or a smallnum- 30 Watson berof fragments: there was nothingto correspondto the open-field systemof northern Europe. Nor do we learnof anycultivated land overwhich peasants exercised common or collectiverights, or of any operationswhich, like the plowingon the manorsof northern Europe,required co-operation (except, of course,the construction andupkeep of irrigation works). Finally, the labor that was required on the land was generallysupplied by sharecroppers;and of all systemsof mobilizing labor to farmlarge estates sharecropping was probablythe one whichmost encouraged innovation on thepart of landownersand theirtenants, both of whomstood to gainfrom in- creasesin productivity.To what extentpaid laborwas important is notclear, though some of thedocuments from Egypt do mention hiredworkers. What is certain,however, is thatagricultural slaves, serfsand tenantsbound to the soil or to a landownerwere rarely found.The agriculturallabor force was by and largefree and, it seems,mobile. It tendedtherefore to movefrom less to moreprofit- able undertakings:presumably from the old agricultureto thenew, and fromlong settled, densely populated areas intonew lands of- feringnew opportunities.Indeed the apparentlygreat mobility of agriculturallabor-which is but one aspectof the mobilityof all classesof peoplein theworld of earlyIslam-may in anotherway have encouragedthe diffusionof the Arab agriculturalrevolution. The Yemeni,Hejazi, Persian,Iraqi and Syrianpeasants who mi- gratedwestward to settlein Egypt,the Maghriband Spain may have had amongtheir numbers the carriersof new cropsand new farmingtechniques. As we knowfrom the studyof industrialtech- nologies,difficult skills are mostreadily diffused by the migration of those who possess them.Only with greatestpains are they learnedafresh by otherpeople in otherplaces. Anotherkind of landed undertaking may also have playedan im- portantrole in diffusingthe agriculturalrevolution. This was the royalgarden. Found almostwherever a rulerhad his seat, and in otherplaces as well,these seem to have been activein introducing exoticplants, including, we may suppose,some of the new crops at the core of the new agriculture.They may also have developed strainsof the new crops better suited to newclimates and new soils, and have been focal pointsin the disseminatingof information abouthow thesewere to be grown.We are told,for instance, that 'Abd al-RahlmanI of Spain collectedin his gardenrarities from everypart of the world.He even sent agentsto Syriaand other AgriculturalRevolution 31 parts of the East to procurenew plants and seeds. A new kind of pomegranatewas broughtto Spain throughhis garden. The date palm, too, was probablyintroduced or re-introducedin the same way. By the tenthcentury the royal gardens at Cordoba seem to have become botanicalgardens, with fields for experimentation with seeds, cuttingsand rootsbrought in fromthe outermostreaches of the world. Otherroyal gardensin Spain also seem to have become, as well as places of amusement,the sites of seriousscientific activ- ity. Ibn al-Abbarrelates that the King's garden in Toledo, the fa- mous Huerta del Rey, was at least in part an experimentalfarm in which easternplants were acclimatized,and new strains,perhaps more suitable to Spanish conditions,produced. An important,re- centlydiscovered geographical manuscript, that of al-'Udbri,states that al-Mu'tasim,a Taifa king,brought many rare plants to his garden in Almeria; these, we are told, included bananas and sugar (both of which, however,we know were already grown in other parts of Spain). At the otherend of the Islamic world, in Tabriz, we findthe garden of the Il-Khans being used to acclimatizerare fruittrees fromIndia, China, Malaysia and Central Asia. Another sign of the seriousnature of these undertakingsis the fact thatsuch gardenswere oftenin the charge of leading scientists:that of the Il-Khans was directedby a Persian botanistwho wrote a book on the graftingof fruittrees; the Huerta del Rey in Toledo was in the chargeof two of Spain's leading scientists,Ibn Bassdl and Ibn Wafid, both of whom wrote importantmanuals of agriculture,the partial textsof which have recentlybeen discovered.Ibn Wafid was also the authorof a book of simples,which gives,inter alia, the names and uses of many of the new plants being introducedinto Spain. Afterthe fall of Toledo in 1085 both scientistsmoved to the south of Spain and continuedtheir work there; Ibn Bassdl planted an- otherbotanical garden in Seville for his new patron,al-Mu'tamid, the Taifa king. Whetherthe manuals of farmngwere also importantin diffusing new crops and new agriculturalpractices is more difficultto say. Quite possiblythey were not. We cannot know how widely they circulatednor what kind of reader they reached, but theiruseful- ness was clearlyreduced by theirrelatively late appearance. The earliestmanuals, The NabateanBook of Agriculture and The Greek Book of Agriculture,date fromthe beginningof the tenthcentury and mustat firsthave been read primarilyin the easternpart of the 32 Watson Islamicworld. But the accountsof geographersand otherwriters of thetenth century show that by thenthe revolution was well under way in the East and was perhapslargely completed. These manualsmust therefore have played only a secondaryrole in popu- larizingpractices already known to enlightenedpeasants and landowners.In this way theymay have broadenedthe scope of a revolutionthat was alreadywell established.In the westernparts ofthe Islamic world, which were touched by therevolution slightly later,these early manuals could have been more important if in fact theyhad a significantwestern readership in the halfcentury after theirappearance. But by 961,the date of The Calendarof Cordoba, the mainelements of the revolutionwere to be foundin partsof Spain and probablyall over the West; hence theseearly eastern manualscould at besthave playedsome role only over a periodof half a century.By the timethe Spanishmanuals appear in the eleventhcentury the revolutionmust have been a fait accompli, needingperhaps only secondary diffusion into areas whereback- ward peasantsand landownershad not heard its message.The summaof Spanish agriculture, the Kitdb al-fildha of Ibn al-'Awwam, writtenin the twelfthcentury, came at a timewhen the classical age of Islamwas alreadyover in theEast and whenMuslim Spain, a latecomerto theGolden Age, was itselfon thebrink of decline.

III The endof the tale is thestory of the decay of Islamic agriculture in generaland thewaning importance of manyof thenew cropsin particular.It beginsat differenttimes in differentplaces. As earlyas theninth century, settlement retreated from parts of theHejaz and Transjordan.Although the reasons for this precocious abandonment ofland are stillobscure and mayhave had nothingto do withwhat was to follow-indeedit ran counterto the immenselysuccessful Abbasidpolicy of 'imara,or developmentof the economythrough densesettlement of the land-it mayhave been the firstsign of a processthat was laterto becomemore general. From the eleventh centuryonwards decline became more evident as almostevery part of theIslamic world was overrunby successivewaves of invaders: by the Seljuks,the Crusaders,the Ayyubids, the Mongols,and the Ottomansin the East, and by the BanfiHill, the Almoravids, theAlmohads, the Normans, and the Spanish reconquistadores in the AgriculturalRevolution 33 West.Although the agricultural history of the Islamicworld under itsnew conquerors is largelyunwritten, one is able to glimpsestages in its decay. It was particularlyevident at the timeof invasions whichoften destroyed irrigation works and causedpeasants to take flight.But the aftermathof invasionssometimes had morelong- lastingeffects. As theyhad come fromregions where agriculture had madeless intensive use of thesoil, the conquerors were on the wholeunsympathetic to the kind of agriculturewhich the early-Is- lamicworld had so brilliantlycreated. They tendedto introduce systemsof farming and land tenurewhich favored cereal crops and grazing,and whichcould accommodateonly with difficultyspe- cialtycrops. Matters were made worse in someareas by thefailure to maintainthe irrigationworks, by the excessivetaxation of the peasantryand thecorruption of thetax collectors, and probablyby a breakdownof therule of law. Militarybenefices, known as iqtac, becameincreasingly prevalent in manyregions at the expenseof otherforms of taxingand administeringthe land; theirholders en- joyeddifferent kinds of immunitieswhich allowed them to reduce thepeasantry to varyingdegrees of dependence,if not actualserf- dom.Long-term development of theland and evenmaintenance of existingcapital were oftensacrificed to higher,more immediate revenues.Land in manyareas came to be usedless intensively. Some was abandoned. The finalblow came from the circumnavigation of Africa and the discoveryof the New World.On old and newcontinents, with large tropicaland semi-tropicalareas, the new cropswhich had been introducedinto the early-Islamic world could be grownmore cheaply thanin the MiddleEast and the Mediterranean.In spiteof high transportcosts, rice, cotton, sugar, indigo and some of the other new cropsbegan coming from Asia and the Americasinto the Is- lamicworld and its Europeanexport markets. By the end of the seventeenthcentury cotton, rice and sugarhad largelydisappeared as cropsfrom the Mediterraneanbasin, where they had once been so important;these crops,long ago introducedinto the Islamic worldas importsubstitutes, had in turnbeen replacedby imports. Theirdisappearance is partof the generaleconomic decline of the Mediterraneanbasin in thisperiod. The voyagesof discoverydid resultin the diffusionof manynew cropsover the earth'ssurface, someof whichwere to be of greateconomic importance, and of- feredto certainnations many other kinds of economicopportuni- 34 Watson ties.But althoughmaize, tobacco and tomatoesspread through the Islamicworld in the centuriesafter the New Worldwas reached, thepossibilities of thenew continentsseemed to have littleinterest to Muslims-thosepeople who had once been so eagerto snap up anynovelty that could giveprofit or amusement.In the processof its decay,the Islamic world had lostits receptivityto the new and had closedin uponitself. ANDREW M. WATSON, Universityof Toronto

APPENDIX

BIBLIOGRAPHICAL NOTE Asthe full bibliography used in my research is vast,I canlist here only someof the main primary sources. The mostimportant of theseare the Arabfarming manuals, of which about fifteen have survived from the pre- Ottomanperiod. The followingare the key authorsand texts:Ibn Wahshiya(?) (wr.903/4?), Al-fildha al-nabatiya (The NabateanBook ofAgriculture), Dar al-KutubCairo, Agric. Ms. 490,a workof greatest importance,in spite of its uncertainauthorship, which has been little studieduntil now on accountof its long and verydifficult text and the absenceof an edition;"Qustis al-Rdmi"' (tr.? early-lOth c.), Al-fillha al-riimiya(The GreekBook of Agriculture) (Cairo, 1876), a workwhich clearlyrelies on earlierByzantine traditions, towhich, however, very im- portantadditions were made, probably at the timeof compilingthe Arabicedition; Ab-d al-Khair (fI. 11th c.?), Kitabal-fildha, B. N. Paris, Ms.4764 fol. 61-180; Ibn Bassdl(?) (d. 1105),Kitdb al-fildha, ed. & tr. J.M. MillaisVallicrosa & M. Aziman(Tetuan: Instituto Muley el-Hasan, 1955); and Ibn al-'Awwam(fl. 12th c.) Librode agricultura,ed. & tr. J.A. Banquieri,2 vols. (Madrid, 1802) Information about these and other survivingArabic agricultural manuscripts is given in thefollowing: C. Cahen,"Notes pour une histoire de agriculturedans les paysmusulmans m'di'vaux,"Journal of the Economic and SocialHistory of theOrient, XIV (1971),63 ff.;J. M. MillasVallicrosa, La cienciageoponica entre los autoreshispanoarabes (Madrid: C.S.I.C., 1954); and Encyclopediaof Islam,2nd. ed., voce "Fildha." Until recently, however, no seriousstudies weremade of the agricultural practices described in thetexts. This gap hadnow been partly filled by the important work of Dr. LucieBolens of theUniversity of Geneva,who has studiedparticularly the sections on soils and irrigationin the writingsof the Hispano-Muslims.See L. Bolens,Les methodesculturales au MoyenAge d'apres les traitsd'agronomieandalous: traditions et techniques,These de doctoratdu 3e cycle presenteda l'Universite de Paris, I; "L'eauet irrigation d'apres les traits d'agronomieandalous au moyen-age(XIe-XIIe sieles) ," Options AgriculturalRevolution 35

mediterrane'enes(1972), 64 if; and "Engrais et protectionde la fertility dans l'agronomiehispano-arabe. XIe-XIIe siecles," Etudes rurales,XLVI (1972), 34 if. Apart fromthe agriculturalmanuals, the works of a large numberof geographersand travelershave been invaluable; a surveyof the literatureup to the middle of the eleventh centuryis given in A. Miquel, La geographichumaine du monde musulman(Paris/The Hague: Mouton,1967) pp. xiii-1;but among the later writersnot covered in this book should be mentioned al-Bakr1,al-Idr5sI, Ibn Batuia, al- Maqriz1,Ndsir-i Khusrau and al-'Umar! (q.v. in Encyclopedia of Islam). Numerousbooks of simplesand workson medicinehave also been useful, of which the most importantis Ibn al-Baitdr (d. 1248) Traite des simples, tr. L. Leclerc, Notices et extraitsdes manuscritsde la Bibio- theque Nationale, XXIII, XXV, XXVI (1877-83); other useful works in this area are listed in R. Y. Ebeid, Bibliographyof Medieval Arabic and Jewish Medicine and Allied Sciences (London: Wellcome Institute, 1971). Finally, three other works are indispensable: Anon. (wr. 961) Le calendrierde Cordoue, ed. & tr. C. Pellat (Leyden: Brill, 1961), an agriculturalcalendar describingthe tasks performedin differentmonths; Ibn Mammdt! (d. 1209), Kitdb qawanin al-dawawin, ed. A. S. 'Atiya, (Cairo: Ministryof Agriculture,1943), a manual for the use of func- tionaries which contains much informationon farmingpractices; and al-Nuwairli(d. 1332), Nihdyatal-arab ft funtinal-adab, 18 vols. (Cairo: Dar al-kutub,1923-65), an encyclopedicwork.