Investigation of provenances of Early Islamic lead glazes from northern Central Asia using elemental and lead isotope analyses

A representative collection of Early Islamic glazed ceramics from eleven sites in southern Kazakhstan were characterized by compositional (n = 95) and lead isotope analysis (n = 33). The ceramics, which date from the 9–15^th c. CE were examined to determine the glaze type, colorants, and opacifiers used by local craftsmen. Several distinct glaze types are present including transparent high-lead glaze (n = 66) and opaque high-lead glaze (n = 10), of which tin-opacified glazes, tin- and antimony-opacified glazes, and antimony-opacified glazes were all identified. The occurrence of antimony-opacified glazes and tin- and antimony-opacified glazes is unattested in this region in the Early Islamic Period and indicates that the local craftsmen in southern Kazakhstan are innovating in their production of opaque glazed ceramics using local raw materials. Lead isotope analysis was employed to identify potential sources of lead, and the results indicate that the craftsmen were obtaining lead from at least two different sources for their glazed production. Using a large comparative database and through the application of Euclidean distance, we were able to identify potential ore deposits from the Central Asian Orogenic Belt, including deposits that were active silver mines during the Medieval Period. These ore sources were local and suggest that potters were obtaining lead for glaze production from within larger acquisition networks. One cluster of samples (n = 8) had a distinct isotopic signature that matched a unique deposit in Xinjiang, China, which indicates craftsmen were not strictly using local sources, but also obtaining lead through long-distance trade networks.