From Susa to Anuradhapura: Reconstructing aspects of trade and exchange in bitumen-coated ceramic vessels between Iran and Sri lanka from the third to the ninth centuries AD

In contrast with artefactual studies of long-distance trade and exchange in South Asia during the Prehistoric and Early Historic periods (Ardika et al. 1993; Gogte 1997; Krishnan and Coningham 1997; Tomber 2000; Gupta et al. 2001; Ford et al. 2005), few scientifically orientated analyses have focused on artefacts from the region's Historic period. During excavations at the ancient city of Anuradhapura, Sri Lanka, a number of buff ware ceramics with a putative organic coating on the interior were recovered (Coningham 2006). Dated stylistically to between the third and ninth centuries AD, analysis of the coatings using gas chromatography-mass spectrometry (GC-MS) and stable isotope analysis (carbon and deuterium) confirmed that the coatings are bitumen-an organic product associated with petroleum deposits. There are no known bitumen sources in Sri Lanka, and biomarker distributions and isotopic signatures suggest that the majority of the samples appear to have come from a single bitumen source near Susa in Iran. The relationship between the bitumen coatings and the vessels is discussed, and it is suggested that the coatings were used to seal permeable ceramic containers to allow them to transport liquid commodities. This study enhances our knowledge of networks of trade and exchange between Sri Lanka and western Asia during Historic times.