Cultural Evolution Process And Plant Remains During Neolithic-Bronze Age In Northeast Qinghai Province

Based on the archaeological investigation at accumulative total to136sites in upper reaches of Yellow River valley, Huangshui River valley, Datonghe River valley, upper reaches of Hei River valley and Qinghai Lake Basin during Neolithic-Bronze Age in Northeast Qinghai Province, as well as8114C radiobarbon dating, combined with archaeological material, the spatial and temporal cultural evolution process was explored. According to collected91soil samples at68key sites for flotation, up to18593of carbonized plant seeds was identified, as well as some auxiliary animal bones as addition in some agricultural underdevelopment area, combined with other archaeological material, the subsistence strategy during every period in different geomorphic units was studied on. The paleoclimate records was took from a loess/paleosol profile near Changning site in Datong County, Qinghai Province, combined with other records from Northeast Qinghai Province and surrounding areas, as well as the modern suitable degree to agriculture and husbandry in different geomorphic units, the driving factors of the spatial and temporal cultural evolution process and subsistence strategy was discussed with time orders and in different geomorphic units. Main conclusion as following:(1) The earliest Neolithic settlements in Northeast Qinghai Province appeared during Late-Yangshao period (5450-5320a BP), mostly distributed in Minhe County located near the boundary of Gansu and Qinghai Province. The first large culture expansion occurred during Early-Mid Majiayao period (5290-4330a BP), archaeology sites distributed westward to Xinghai County. While the culture shrinked eastwasrd (low altitude area) during late Majiayao period (4280-3910a BP). The second large culture expansion during Neolithic-Bronze Age started from Qijia culture (4260-3580a BP), and the spatial distribution of archaeological sites extended westwasd to Qinghai Lake Basin. After Qijia culture, Xindian (3640-2530a BP), Kayue (3640-2140a BP) and Nuomuhong Culture developed from east to west in this area. The distribution boundary of Xindian and Kayue culture were Ledu-Xunhua counties, and Kayue culture affected the west area.(2) Agriculture based on broomcorn millet firstly appeared during Late-Yangshao period. This type of agriculture system was continued during Early-Mid Majiayao period, and a small amount of Cannabis sativa was found at this time. In late Majiayao period, foxtail millet took the same place with common millet. The farming during Qijia period was still dominated by millet, while triticeae crops first emerged. In Xindian period, triticeae crops became main crop in Huangshui River Basin, while the triticeae crops just occupied a certain proportion in Guanting basin. However, the triticeae crops were the main crop in Kayue Culrure region, and barley occupied the leading position.(3) Foxtail millet and common millet were first found at Hulijia site in Guanting Basin (5450a BP); triticeae crops were at Jinchankou site (3960a BP) in Datong River valley, Cannabis sativa was at Hurere site (4620a BP) in Guanting Basin, buckwheat was at Yingpandi site (2550a BP) in Huangshui River valley, oat was at Hongyaxiayinpo site in Huangshui River valley (Kayue period).(4) Pollen and other climate proxies in Changning profile showed that5830-5070a BP was a warm and wet period; climate deteriorated and turned to cold and dry after5070a BP; climate turned warm and wet again around4700a BP.(5) Climate change and agriculture expansion were the main factors affecting the Neolithic cultural evolution. In Qijia period, the short climate improvement prompted culture expansion, and human survival strategy adjustment may also play an important role during this period. After the Bronze Age, the ability of prehistoric human for adapting to climate change increased significantly, subsistence strategy became the main factor for human surviving and cultural expansion at clod and dry environment in northeast edge of the Qinghai-Tibet plateau.This study made a large promotion in better understanding about the Neolithic-Bronze cultural evolution process, human subsistence selection and their driving factors in Northeastern Qinghai Province, and will push forward the coupling relationship research between environmental change and human adaption.