Prehistoric sheep/goats husbandry in Xinjiang, China—Evidence from bone stable carbon and nitrogen isotopes

Sheep and goats have been introduced into northwest China as important livestock for some four thousand years. The frequency of sheep/goats’ bones in prehistoric archeological sites in Xinjiang can be a proof of their importance in people’s life. This study focuses on food reconstruction of prehistoric sheep/goats across Xinjiang to illustrate whether there is a difference on sheep/goats husbandry. Bone samples from 11 sites were isotopically analyzed together with 4 sets of published data, 220 pairs of sheep/goats bone stable carbon and nitrogen isotopes in total from 15 sites across Xinjiang with time span of ca, 4000 cal BP to ca. 2000 cal BP were produced. 9 sites each with sample number no less than 10 were further studied. It revealed that generally sheep/goats from 4 oasis sedimentary farming societies have both higher ¹³C values and higher ¹⁵N values, although highly fluctuated. It is highly likely that C₄ plants such as foxtail millet or common millet must have not been a stranger around their environment. As for their remarkably high ¹⁵N values, drought stress in arid environment may have been one reason, fertilized soil after long time relatively intensive human activity may have also contributed to this. In the meanwhile, sheep/goats from 5 pastoralism or transhumance societies have homogenous and more negative ¹³C values, most of which are lower than -18‰, meaning that there was barely no C₄ plants in their diet. In contrast, ¹⁵N values of them are lower than that of farming societies as a whole but more scattered, seasonally different pastures with diversified ¹⁵N background could be the reason.