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Research paper The Holocene 0(0) 1–13 Variable monsoons and human ! The Author(s) 2020 Article reuse guidelines: adaptations: Archaeological and sagepub.com/journals-permissions DOI: 10.1177/0959683620919976 palaeoenvironmental records during the journals.sagepub.com/home/hol last 1400 years in north-western India Anil K Pokharia1 , Jeewan Singh Kharakwal2, Shalini Sharma1 , Michael Spate3, Deepika Tripathi1 , Ashok Priyadarshan Dimri4 , Xinyi Liu5, Biswajeet Thakur1, Sadhan Kumar Basumatary1, Alka Srivastava6, Kamalesh S Mahar1 and Krishna Pal Singh2 Abstract We present the first systematic evaluation of the relationship between the archaeological and palaeoclimatic record from north-western India during the past millennium, from the urban site of Chandravati. The rarity of Medieval sites, systematic excavations and multi-disciplinary work in the subcontinent obscure the impact of two distinct climate anomalies À the ‘Medieval Warm Period’ (‘MWP’, 740 À 1150 CE), followed by the ‘Little Ice Age’ (‘LIA’, 1350 À 1850 CE). The finds from the archaeological site indicate the presence of winter and summer crops, suggesting the region was likely warm and mild humid during pre-Medieval period (ca. 600 À 800 CE). During Medieval times (between ca. 800 À 1300 CE), a diversification of the crop assemblage suggests that the region was under a warm and humid climate, corresponding to the ‘MWP’, driving increased monsoon precipitation. During the post-Medieval period (ca. 1350 À 1800 CE), drought-resistant millets and other summer pulse crops indicate the region probably expe- rienced weak SW monsoon precipitation coinciding with globally recognised ‘LIA’. These interpretations are supported through phytolith data from the archaeological deposit broadly indicating two phases, the first being a period of diversified agricultural/anthropogenic activity (ca. 600 À 1350 CE), followed by a period dominated by drought-resistant crops (ca. 1350 À 1800 CE). Pollen data from a proximal lake corroborate the warm and humid phase ca. 800 À 1400 CE, with strong representation of warmÀhumid favouring tropical forest taxa, followed by non-arboreal indicators of a drier more open landscape ca. 1500 À 1800 CE. These environmental changes may have combined with other historic and institutional factors that led to the ultimate abandonment of the city. These changing cropping patterns, vegetation and cultural developments provide insight into past human response to climate change as well as important lessons for modern societies in exploring sustainable agricultural strategies to future climate change. Keywords agriculture, Chandravati, Little Ice Age, Medieval Warm Period, north-west India, palaeoclimate, past millennium Received 19 November 2019; revised manuscript accepted 6 March 2020 Introduction contextualised against changes in material culture or settle- Examining economic and environmental changes in the ment pattern (Petrie et al., 2017; Pokharia et al., 2017). The archaeological and palaeoclimatic records provide some of entanglement of ecological, economic and cultural factors the most compelling insights into the growth, collapse or indicate that for ongoing social stability to be maintained, resilience of large urban agglomerations (Bar-Oz et al., strategies for resilience to environmental stresses are crucial. 2019; Cookson et al., 2019; Penny et al., 2019). In South Asia, studies of this nature have tended to focus on fluctua- tions of the Indian Summer Monsoon (ISM) as a driver of 1Birbal Sahni Institute of Palaeosciences, India the urbanisation and de-urbanisation of the prehistoric 2 Harappan Civilisation in the northern subcontinent, ca. Institute of Rajasthan Studies, India 3Department of Archaeology, The University of Sydney, Australia 2500–1700 BCE (Dixit et al., 2018; Giosan et al., 2012, 4 School of Environmental Sciences, Jawaharlal Nehru University, India 2018; Prasad et al., 2014) Building on the works of Weber 5Department of Anthropology, Washington University in St. Louis, USA (1999) and Madella and Fuller (2006), archaeobotanical 6Department of Botany, Dayanand Girls P.G. College, India studies characterised variations in economic plant assemb- Corresponding author: lages as indicative of strategies aimed to mitigate the Anil K Pokharia, Birbal Sahni Institute of Palaeosciences, 53 University impacts of climate change, including crop diversification Road, Lucknow 226007, Uttar Pradesh, India. or shifting patterns of summer/winter cultivation Email: [email protected] 2 The Holocene 0(0) The impacts of historic period climate events in South Desert (Prasad et al., 1997), as well as pollen studies from Asia, such as the ‘Medieval Warm Period’ (‘MWP’) and Madhya Pradesh (Chauhan and Quamar, 2012; Quamar ‘Little Ice Age’ (‘LIA’) during are relatively understudied, and Chauhan, 2014). Highly resolved speleothem records as research on social and political change has tended to focus (e.g. Kathayat et al., 2017) prove data for fluctuating on the fragmentation of centralised Indian Dynasties, inva- regional rainfall patterns, which when compared with sions from Central and West Asia and the eventual integra- other proxies may allow insights into localised ecological, tion of the Mughal Empire (Chandra, 2003). cultural or economic responses. In general, local-scale envi- Here we examine the growth, expansion and eventual ronmental studies have tended to not focus on the ISM abandonment of the urban site of Chandravati in during the recent Holocene, and the timing and impacts Rajasthan, NW India. We present new on-site archaeolog- of the ‘MWP’ and ‘LIA’ are only briefly discussed (Rawat ical data as well as proximal environmental data to link et al., 2015a, 2015b; Trivedi and Chauhan, 2009). changing local environmental conditions to global climate events, namely, the ‘MWP’ and ‘LIA’. We consider the Site location and context impacts of historic climate events such as the ‘MWP’ and ‘LIA’ on the ISM. Climate variations are compared with Rajasthan is the largest and westernmost state in modern social and economic changes in the region, and provide India and can be divided into four physiographic regions: context for understanding the ways in which resilience of the Thar Desert in the west; the Aravalli hills running from the population was maintained through economic strategies the SW to NE; the eastern alluvial plains and the southeast such as selective seasonal cultivation or crop diversification. plateau (Swain et al., 2012). The state is more arid than other regions of India, with the Thar Desert receiving the extreme lowest rainfall in modern India (below 100 mm), Timing and impacts of the ‘MWP’ and ‘LIA’ in Asia and the rest of the state receiving less than 600 mm precip- Early syntheses of historical accounts and climate proxies itation per year (Singhvi and Krishnan, 2014). Modern sur- have tended to focus on Europe, allowing the identification face observation data from the 100 years between 1901 and of a period of warming between the 10th and 13th centuries, 2016 suggest an average summer peak of 40C in May, prior followed by a cooling anomaly of up to 1C until the 19th to the onset of the ISM, and a low of around 8 to 9C century (Lamb, 1965). Though the timing of the onset of during the post-monsoonal winter in December to cooling conditions is still debated, this general chronology January (Indian Meteorological Department (IMD), has allowed for archaeologists and historians to consider 2018). Agriculture is primarily rain-fed (Gupta, 2016) and economic and social changes in Europe as a response to major cereal crops are pearl millet, wheat, maize and sor- climate cycles (Aberth, 2012; Fagan, 2000). More recently, ghum. Chickpea, moth and mung beans are the main pulses studies have focussed on the timing and impact of the cultivated in the region. These are typically grown in a bi- ‘MWP’ and ‘LIA’ in Asia, in particular, the spatial distri- seasonal system, with wheat and chickpea as winter/rabi bution and forcing factors involved of fluctuations in the crops, and millets and other pulses as summer/kharif types East Asian Summer Monsoon (Chen et al., 2015; Kamae (Swain et al., 2012). et al., 2017). The onset of the ‘LIA’ in China from the mid- Chandravati (2426017.800N, 7244032.200E) is located in 16th century has been linked to famines, north–south the foothill zone of Mt Abu in the southern Sirohi district migrations and social unrest that had severe implications of Rajasthan, among the Aravalli hills (Figure 1). The for the stability of the Ming and Qing Dynasties (Wu ancient settlement is situated close to the confluence of the et al., 2018; Xiao et al., 2015). Sevarni and Banas rivers. The larger Banas is oriented In northwest India, Agnihotri et al. (2002) correlated fluc- roughly north–south with fertile terrain on both banks, tuating biogenic carbon and nitrogen discharge into the entering Gujarat at Mawal about 4 km downstream of Arabian Sea against insolation variation, finding a relation- Chandravati. Both rivers are comparatively shallow and ship between increased surface productivity and higher cut into underlying bedrock. The Sevarni has a flood plain summer insolation. These trends indicated a general increase about 300 m broad at river-bends, above which are undulat- between 900 and 1400 CE, followed by a decline interpreted ing plains. Between the two rivers, one of these plains forms a as the onset of the ‘LIA’. Drawing on this study, Uberoi sub-triangular area with its base towards the mountains and (2012)