Tianshanbeilu and the Isotopic Millet Road: reviewing the late Neolithic/Bronze Age radiation of human millet consumption from north China to Europe

The westward expansion of human millet consumption from north China has important implications for understanding early interactions between the East and West. However, few studies have focused on the Xinjiang Uyghur Autonomous Region, the vast geographical area directly linking the ancient cultures of the Eurasian Steppe and the Gansu Corridor of China. In this study, we present the largest isotopic investigation of Bronze Age China (n = 110) on material from the key site of Tianshanbeilu, in eastern Xinjiang. The large range of delta C-13 values (-17.6 parts per thousand to -7.2 parts per thousand; -15.5 +/- 1.2 parts per thousand) provides direct evidence of unique dietary diversity and consumption of significant C-4 resources (millets). The high delta N-15 results (10.3 parts per thousand to 16.7 parts per thousand; 14.7 +/- 0.8 parts per thousand) likely reflect sheep/goat and wild game consumption and the arid climate of the Taklamakan Desert. Radiocarbon dates from four individuals indicate Tianshanbeilu was in use between 1940 and 1215 cal bc. The Tianshanbeilu results are then analysed with respect to 52 Bronze Age sites from across Eurasia, to investigate the spread and chronology of significant human millet consumption and human migration. This isotopic survey finds novel evidence that the second millennium bc was a dynamic period, with significant dietary interconnectivity occurring between north China, Central Asia and Siberia. Further, we argue that this 'Isotopic Millet Road' extended all the way to the Mediterranean and Central Europe, and conclude that these C-4 dietary signatures of millet consumption reflect early links (migration and/or resource transfer) between the Bronze Age inhabitants of modern-day China and Europe.