The transformation of cropping patterns from Late Neolithic to Early Iron Age (5900–2100 BP) in the Gansu–Qinghai region of northwest China

The Gansu–Qinghai region lies in the key position for trans-Eurasian cultural exchange, and hence investigations of the history of agricultural development in this region are significant for understanding the spatiotemporal evolution of prehistoric crop dispersal in Eurasia. However, systematic archaeobotanical studies concerning the history of the development of prehistoric agriculture in this area are scarce. Here, based on archaeobotanical analysis and radiocarbon dating at the Jinchankou site, we investigated the history of agricultural development in the Datong River valley during the Qijia culture. Combined with previous archaeobotanical studies of the Gansu–Qinghai region, we explored the diachronic changes in the cropping patterns from the Late Neolithic to the Early Iron Age. The results suggest that millet remained the most important subsistence plant during 4100–3700 BP, while barley and wheat were first cultivated around 3900 BP at the Jinchankou site. Humans only cultivated foxtail and broomcorn millet in the Gansu–Qinghai region with a high level of agricultural management during 5900–4000 BP. Barley and wheat were added to the agricultural system in the area during 4000–3600 BP, although they played a subsidiary role compared with millet. During 3600–2100 BP, barley played an increasingly important role in the Gansu–Qinghai region but with evident differences among geomorphic units, and there was an obvious decrease in agricultural management level. It is likely that the transformation of cropping patterns and agricultural management levels in the Gansu–Qinghai region from 5900 to 2100 BP was primarily promoted by prehistoric trans-continental cultural exchange and secondly by climate change in the area.