Ancient Irrigation and Buddhist History in Central India: Optically Stimulated Luminescence Dates and Pollen Sequences from the Sanchi Dams

Article excerpt


This paper presents the results of a recent pilot project aimed at obtaining optically stimulated luminescence (OSL) dates from a group of ancient irrigation dams in central India. The dams are all situated within an area of 750 [km.sup.2] around the well-known Buddhist site of Sanchi, the latter established in c. third century B.C. and having a continuous constructional sequence up to the twelfth century A.D. They were documented during earlier seasons of the Sanchi Survey, initiated in 1998 in order to relate the site to its wider archaeological landscape. The pilot project builds upon earlier hypotheses regarding the chronology and function of the Sanchi dams and their relationship to religious and political history in Central India. The principal suggestion is that the earliest phase of dam construction coincided with the rise of urbanization and the establishment of Buddhism in central India between c. third and second centuries B.C.; and that they were connected with wet-rice cultivation as opposed to wheat, the main agricultural staple today. Similarities with intersite patterns in Sri Lanka, where monastic landlordism is attested from c. second century B.C. onward, have also led to the working hypothesis that the Sanchi dams were central to the development of exchange systems between Buddhist monks and local agricultural communities. The pilot project focused on two out of a total of 16 dam sites in the Sanchi area and involved scraping back dam sections created by modern road cuttings. This cast new light on aspects of dam construction and allowed for the collection of sediments and ceramics for OSL dating. The results confirmed the suitability of local sediments to OSL dating methods, as well as affirming our working hypothesis that the dams were constructed--along with the earliest Buddhist monuments in Central India--in the late centuries B.C. Sediment samples were also collected from cores hand drilled in the dried-up reservoir beds, for supplementary OSL dating and pollen analysis, which shed useful insights into land use.

Keywords: irrigation, dams, rice agriculture, OSL dating, pollen analysis, ancient India, spread of Buddhism, religious change, theories of state.

This essay presents the results of a recent pilot project aimed at obtaining optically stimulated luminescence (OSL) dates from a group of ancient irrigation dams in central India. (1) These dams were initially documented between 1998 and 2002 during a multiphase exploration project carried out over 750 [km.sup.2] around Sanchi (Figs. 1 and 2), a well-known Buddhist site in Madhya Pradesh recently accredited with a UNESCO World Heritage status (Shaw 2000, 2004a, 2004b, 2005, forthcoming; Shaw and Sutcliffe 2001, 2003a, 2003b, 2005). The Sanchi Survey was aimed at relating the site's Buddhist monuments to their wider archaeological landscape, resulting in the systematic recording of 35 additional Buddhist sites, 145 habitational settlements, over 1000 sculptures, numerous painted rock shelters, and the 16 dams discussed here. These data have provided an empirical basis for building an integrated model of religious and economic change in ancient India, assessing how Buddhism established itself in new areas, and relating its spread to other key processes such as urbanization, state formation, religious change, and the development of new agrarian systems.


A number of hypotheses relating specifically to the dams have been presented in earlier papers, based on surface remains and present-day hydrological and climate data (Shaw and Sutcliffe 2001, 2003a, 2003b). These can be summarized as follows: (1) The earliest phase of dam construction occurred approximately between the third and first centuries B.C., in keeping with the main building phases at Sanchi and neighboring Buddhist sites; (2) they were built to provide irrigation, probably for rice, as a response to the increased population levels suggested by the distribution of habitational and Buddhist sites in Vidisha's hinterland; (3) they were part of a cultural package that accompanied the spread of Buddhism, urbanization, and the development of centralized state polities in the late centuries B. …