Early To Middle Holocene Human Activities And Environmental Context In The Qilian Mountains Region

The Qinghai-Tibetan Plateau is one of the harshest natural environments in the world,so human adaptation to its extreme environment,such as high cold and low oxygen,and low biological productivity,has become a hot issue in domestic and international research.The Qilian Mountains region is a marginal mountainous region in the northeastern part of the Qinghai-Tibetan Plateau with a long history of human activities.From the early and mid-Holocene human activities in the Qilian Mountains,they are mainly distributed in the eastern Qinghai Lake Basin,the He-Huang Valley and the northern foothills of the Qilian Mountains,while human activities in the central mountains and the west are less.In recent years,the team Qilian Mountain central Heihe valley fieldwork found the Huangzangsi site,the site of HZS1 microliths site for the current central Qilian Mountain earliest human activity remains.In this paper,human activity remains such as lithics,photoluminescence dating samples and environmental indicator samples were systematically collected from its stratigraphic site HZS1;human activity remains such as lithics and pottery shards were collected from the surface of sites HZS2 and HZS3.Afterwards,the human activity remains(stone tools and pottery shards)were identified and analyzed by the artifact type method;the 4 OSL chronological samples and 70 environmental index samples(particle size,magnetization rate,chromaticity,TOC,charcoal debris,fungal spores,pollen)were analyzed by the experimental analysis method;in addition,the activity routes of prehistoric people were simulated by GIS technology in combination with the published data of prehistoric people on the Tibetan Plateau and surrounding regions In addition,GIS technology was used to simulate the activity routes of prehistoric people,combining the published data of prehistoric people on the Tibetan Plateau and surrounding regions.On this basis,we reveal the activity time,cultural attributes,relationship between ancient human activities and environmental evolution of prehistoric populations in the early and middle Holocene of the Qilian Mountains,and the exchange and connection between prehistoric populations in the Qilian Mountains and neighboring regions.The main conclusions are as follows.(1)The results of 4 OSL dating samples from the HZS1 profile show that they are dated between 13.7 and 5.1 ka.The four small flakes and two microblades fragments excavated from the stratum of HZS1 profile indicate that the prehistoric group was a hunter-gatherer using microblade technology,and they used high-quality chalcedony stone to beat stone tools with mature beating skills.Using the dating results combined with the location of the microliths excavated from the stratum,It is inferred that prehistoric humans were active in this area during 8.0～6.1 ka.5 sherds of fine clay pottery and 1 sherd of coarse sand-laminated pottery found at sites HZS3 and HZS2,respectively,suggest that the Siba culture people may have spread to the Heihe valley in the central Qilian Mountains,while the Kayue culture people had extensive activities in this area.(2)The results of environmental proxies such as grain size,magnetization rate,chromaticity,TOC and pollen in the HZS1 profile show that during 13.7～10.5 ka,forests,alpine grasslands and alpine meadows were developed in the area,and the climate gradually tended to be humid,but wind and sand activities were more frequent and the soil-forming effect was poor.During the period from 10.5 to 8.0 ka,the forest spread further,the alpine grassland and alpine meadow vegetation began to fluctuate and strengthen,and the wind and sand activities began to weaken.During 8.0～6.0 ka,the content of spruce spp.in forest vegetation decreases and the content of pine spp.increases,alpine grassland and alpine meadow vegetation develop significantly,the climate is warmer and wetter,wind and sand activities decrease significantly,and soil formation gradually increases.During 6.0～5.1 ka,the forest vegetation is at a lower development level,mainly developing alpine grassland and alpine meadow,the climate is warmer and wetter,the clay content increases significantly,the soil-forming effect increases significantly,and the paleosol begins to develop.(3)The prehistoric human activities in the Qilian Mountains are closely related to the environmental evolution.During the period 11.7-8.0 ka,the climatic environment in the Qilian Mountains gradually became wetter,wind and sand activities decreased,and hunter-gatherers using microliths technology were concentrated in the environmentally superior Qinghai Lake basin,mainly carrying out short-distance,small-scale seasonal migration activities.During the period from 8.0 to 6.0 ka,the natural environment in the Qilian Mountains improved significantly and hunter-gatherer populations spread from the Qinghai Lake Basin to other higher altitude areas.The Heihe valley was richer in flora and fauna during this period,and the Huangzangsi microliths population was active there.During the period 6.0～4.0 ka,the humid climatic environment of the Qilian Mountains began to change,and the microliths technology in the region began to decline,and the corn crop agriculture and livestock economy began to gradually emerge.During the Middle and Late Neolithic,agricultural populations spread to the Heihe Valley in the central Qilian Mountains,and livestock activities may have occurred in this area.(4)Using the results of the expansion route of prehistoric people in the early and middle Holocene of Qilian Mountains area simulated by GIS in this paper,combined with the information of prehistoric human activities in Qilian Mountains area and its adjacent areas.This paper suggests that the Heihe valley may be a major transportation route for human migration and exchange in the mountainous areas on the northeastern edge of the Tibetan Plateau during this period,and the HZS1 site may be a hunting site on the activity route of hunter-gatherer groups.