From necessity to choice: dietary revolutions in west China in the second millennium BC

This article explores the context of the long-distance translocation of crops in prehistory. We draw upon contrasts in the isotopic signatures of Southwest Asian crops, including wheat and barley - C-3 plants, compared to Asian millets - C-4 plants, to investigate a key region of trans-Eurasian exchange, the Chinese province of Gansu. The isotopic results demonstrate that in Gansu province prior to 2000 cal. bc, the staples were millets. Between 2000 and 1800 cal. bc, there was a significant shift in staple foods towards the Southwest Asian crops. In the broader regional context, however, it would seem that these novel crops were not consumed in large quantities in many parts of China during the second millennium bc. This suggests that, while the Southwest Asian crops were adopted and became a staple food source in Gansu province in the second millennium bc, they were disregarded as staple foods elsewhere in the same millennium.