A GIS Approach to Finding the Metropolis of Rhapta

CHAPTER 6 A GIS Approach to Finding the Metropolis of Rhapta Carl Hughes and Ruben Post The Periplus of the Erythrean Sea is a description of trade networks in the western Indian Ocean written as a guide for merchants (Casson 1989: 5). This text provides a description, varying in detail, of a multitude of regions, including the geographic features, settlements, ports, and peoples to be found in each. The original text, dating to approximately 30–40 CE, no longer survives, but a copy, believed to date to the tenth century, has been preserved and is currently housed in Heidelberg (Graf 1994: 143). The southernmost location mentioned in the text is the port of Rhapta, on the East African coast. This port is also mentioned in Ptolemy’s Geography, a second-century CE geographical account, in which it is termed a mētropolis and located “a short distance from the sea” (mikron apothen thalasses̄ ), that is, at the mouth of the Rhaptos river which flowed into the Indian Ocean (4.7.12). The exact location of Rhapta has been the subject of a lengthy historical debate owing to a lack in the text of any description of recognizable geographic features associated with, and the absence of any notable archaeological sites that can unequivocally be attributed to, the port (Hoyle 1967: 95; Horton 1990: 97; Kirwan 1986: 99). C. Hughes (*) McGill University, Montreal, QC, Canada R. Post University of Pennsylvania, Philadelphia, PA, USA © The Author(s) 2016 135 G. Campbell (ed.), Early Exchange between Africa and the Wider Indian Ocean World, DOI 10.1007/978-3-319-33822-4_6 136 C. HUGHES AND R. POST It is universally accepted that Rhapta was located somewhere on the Indian Ocean littoral of Azania (as East Africa is termed in the text) (Casson 1989: 141; Datoo 1970a: 66), a region corresponding to the southern extent of the modern Swahili coast, between the Somalia– Kenya border and northern Mozambique. It is also known that the name “Rhapta” comes from the ancient Greek rhapta ploiaria, meaning “sewn boats” (Periplus 16), the typical mode of transport employed at the time in this region (Casson 1989: 61). Moreover, it is apparent that Rhapta was a very important commercial port in the Indian Ocean World (IOW) in the first two centuries CE which the author notes was a major source of tortoise shell and soft ivory, as well as a lesser source of rhinoceros horn and nautilus shell (Periplus 17; Casson 1989: 61). The tortoise shell found in Rhapta was a popular commodity because, as the author notes, it was considered second in quality only to that obtained from India (Periplus 17), while a depletion of ivory sources available to Red Sea ports in the period the Periplus was written made this port a major source of soft ivory for IOW markets (Datoo 1970a: 73). The importance of this settlement as a center of trade is further indicated by Ptolemy’s designation of it as a mētropolis, a term used to refer to the most important city in a region, and thus usually also to major commercial hubs (Liddell et al. 1940: s.v. mētropolis, A.III). The various modern commentaries on the Periplus have indicated three possible locations for Rhapta, all of them in modern Tanzania: the environs of Dar es Salaam; Pangani; and the Rufiji delta (Hoyle 1967: 95; Horton 1990: 97; Kirwan 1986: 99; Datoo 1970a: 66). By examining the information found in the Periplus, comparing it to that furnished by the later Geography of Ptolemy, and analyzing the resulting data in GIS, we will demonstrate the most likely modern site of Rhapta, as well as the locations of several nearby sites mentioned in both texts. The Periplus is divided into 66 chapters, starting at the northern edge of the Red Sea. As the chapters progress, the author describes sites along the route heading south, reaching the Horn of Africa by chapter 12; in chapter 18, the description of the African coast is concluded with the region around Rhapta. From chapters 19 to 66, the author then describes his travels to and around India, beginning again from a port in the Red Sea. The description of the east coast of Africa begins at the tip of the Horn of Africa with a site referred to as the Spice Port (to tōn Arōmatōn emporion), corresponding to the last promontory of the north Somalia coast. The geography of the area fits the description of the text in that it is exposed to the north but protected from the south. The location of the A GIS APPROACH TO FINDING THE METROPOLIS OF RHAPTA 137 so-called Spice Port was likely the modern village of Daamo on the Horn, at which pottery of eastern Mediterranean origin dating to the Roman period has been discovered (Chittick 1979: 275; Reade 2013: 449–450) (Map 6.1). Chapter 13 begins with the village of Tabai, the author stating that after sailing a distance of 400 stades (a unit of distance to be discussed later in this chapter) along a peninsula one will reach a port of trade known as Opone. Tabai must be in the bay of Charo Hordio due to the distance mentioned to Opone (Casson 1986: 181). Excavations at the modern site of Ras Hafun have uncovered numerous fragments of pottery from Mesopotamia, Iran, Egypt, and the eastern Mediterranean dating to between the first century BCE and the first century CE, suggesting that this was the location of Opone (Chittick 1976: 133; Smith and Wright 1988; Reade 2013: 449). The unique geography of this site also supports this theory, as it matches the statement in the Periplus that along this route lies a peninsula “towards which the current sets” (kath’ hon topon kai ho rhous helkei; Casson 1986: 181), while the journey around it roughly equates to 400 stades. Map 6.1 The East African Coast according to the Periplus (drawn by Carl Hughes of the Indian Ocean World Centre (IOWC), McGill University) 138 C. HUGHES AND R. POST In Chapter 15, after Opone, the coast is said to trend to the south, marking the beginning of the Small and Great Bluffs of Azania (mikra Apokopa kai megala tēs Azanias). Based on modern satellite images and digital elevation models, it is clear that these bluffs are almost certainly those marking the Somali coastline from approximately 10 degrees down to 7.5 degrees north. At the end of these bluffs begin a series of sandy beaches, almost certainly the Small and Great Beaches, which according to the Periplus extend for another six “runs.” According to Guillain (1856: 103 in Casson 1989: 139), the beaches stretch a total distance of 607 km, from Ras al Khyle to a location just short of short of Washeikh, Somalia. Chittick (1976: 120) asserts, however, that the distance to Washeikh is 704 km. Each figure is a little too high to correspond to the most accurate measure for a run, 1000 stades; nonetheless, if we add the length of the Beaches and the Bluffs, their combined distance should be between 900 and 1110 km (Guillain 1856: 103 estimates 1007 km; Chittick 1976: 120 estimates 1178 km). It is likely that the beaches actually begin at a latitude of about 7.5 degrees north and end at a latitude of about 2.4 degrees, thus corresponding to a distance of 1020 km, similar to Guillan’s estimate. After the beaches come the Runs of Azania, seven in total, starting with the Sarapion Run, then the Nikon Run, and continuing on, separated by daily stops up to the Pyralaoi Islands. The Pyralaoi Islands are the farthest southern geographic feature mentioned by the Periplus along the East African coast that can be identi- fied with relative certainty. These islands are Pate, Lamu, and Mandra. The author then notes the existence of a feature associated with these islands known as the Canal, which is almost certainly the bay that forms a natural canal around Pate. From here, the text states that “a little more towards the west after two night-and-day runs, lying due west … comes Menouthias Island, about 300 stades from the mainland” (Periplus 15) “a little more towards the west after two night-and-day runs, lying due west … comes Menouthias Island, about 300 stades from the mainland.” It is from this vague passage, unfortunately corrupt, that confusion arises. In order to identify Menouthias Island, we can only rely on a calculation of the distance provided by this text, and thus we must ascertain the correct measures for a run and stade. Kirwan (1986: 101) argues that it is impossible to quantify the distance of a night-and-day run without knowing the weather or sea conditions at the time when the trip was undertaken, because a run is simply a measurement of the distance traveled within a specific time period. Casson (1989: 278), however, referring to Bunbury (1879: 455), argues that it is pos- A GIS APPROACH TO FINDING THE METROPOLIS OF RHAPTA 139 sible to quantify these units based on distances calculated by Eratosthenes and Marinos. The texts of these ancient geographers mention distances in runs and stades, which had become standard geographic units of measurement by the time the Periplus was written. Casson (1989: 278) uses these texts to hypothesize the length of a night-and-day run as 1000 stades. But in order to understand this measurement, we must know the length of a stade, which itself has been the subject of debate. Estimates for the length of this unit range from 157 to 185 m.

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