The emergence, development and regional differences of mixed farming of rice and millet in the upper and middle Huai River Valley, China

Mixed farmingof rice and millet is one of the basic agricultural modes in the upper and middle Huai River Valley (HRV). According to the latest data, this agricultural mode appeared during the middle and late Peiligang Culture (7.8–7.0 ka BP) in the upper HRV, and then became a common subsistence economyin the end of the Neolithic (5.0–4.0 ka BP) in both the upper and middle HRV. However, it is still not clear how this mixed farmingdeveloped in the upper HRV after its occurrence, nor are the regional differences in the development of mixed farmingbetween the upper and middle HRV during the Neolithic completely understood. In this paper, flotation and starch analyses were conducted on samples from eight archaeological sites in the upper and middle HRV. The results indicate that the mixed farmingof rice and millet first appeared in the later phase of the middle Neolithic in the regions of the Peiligang Culture, then developed quite rapidly in the late Neolithic (6.8–5.0 ka BP), finally becoming the main subsistence economyat the end of the Neolithic in the upper HRV. However, there are obvious differences in the emergence and development of agriculture between the middle and upper HRV. Rice farming was the only agricultural system during the middle Neolithic, lasting until the end of the Neolithic, when mixed farmingappeared in the middle HRV. Furthermore, although mixed farmingappeared in both the upper and middle HRV during the end of the Neolithic, the roles of rice, foxtailmillet and broomcorn millet in the subsistence economywere not the same. In general, millet was more widely cultivated than rice in the upper HRV, but rice occupied the same or a slightly more prominent position in the middle HRV at the end of the Neolithic. These results are significant for understanding the process of agricultural development and transformation, as well as human adaptation to climatic and cultural variability duringthe Neolithic.