Study On The Spatial-Temporal Distribution Of Holocene Human Occupation Sites Around The Junggar Basin And Its Climatic And Environmental Influence Factors

Xinjiang is located in the heart of the arid region of inland Asia,a place where Chinese and Western cultures gather,and an important part of the ancient Silk Road,with a very rich site of ancient human activities.Studying the relationship between the spatial and temporal distribution of human activity sites and geographical environment during the Holocene around the Junggar Basin not only clarifies the relationship between the activities of ancient humans and climate change in typical arid regions but also provides a reference point for modern society to find suitable survival strategies under today's changing climate.Based on the platform of Arc.GIS,this study conducts a spatiotemporal analysis of the sites of human activity around the Junggar Basin in the prehistoric period and historical period(The historical period is dates back to 1912 AD,at the end of the Qing Dynasty).The specific characteristics of the spatial distribution of human activities were analyzed by analyzing the geomorphology,elevation,center of gravity,site direction,nuclear density and agglomeration of human activity sites.Then,the characteristics and changes of landforms,vegetation and climate in the region are comprehensively analyzed,including changes in humidity and vegetation types,to sort out the basic characteristics of the climate environment since the Holocene around the Junggar Basin,and discuss the relationship between human activities,geographical environment and climate change to analyze the characteristics of human-land relations and their main influencing factors in different periods.The main results are as follows:(1)There are 1692 sites of human activity since the Holocene around the Junggar Basin.From the perspective of time distribution,in the pre-historical period,there were13 Neolithic Age,81 Bronze Age,and 561 in the early Iron era.During the historical period,human activities showed a "W"-shaped development.The high active period was the Han Dynasty,the Sui and Tang Dynasties,and the Ming and Qing Dynasties.The low active period was the period of the Three Kingdoms,the Two Jin,Southern and Northern Dynasties periods,and the Song,Yuan,and Liao Dynasties.The specific manifestations of human activities are 593 in the Han Dynasty,36 in the Three Kingdoms,Two Jin,Southern and Northern Dynasties periods,183 in the Sui and Tang Dynasties,31 in the Song,Yuan,and Liao Dynasties,and 194 in the Ming and Qing Dynasties.(2)From the perspective of spatial distribution,the Holocene human activity sites around the Junggar Basin are all clustered distribution,and the overall pattern is changed from "Northwest-Southeast" to "East-West" pattern,indicating that the scope of human activities extends from the southeast to the west.Compared with the early historical period,the sites of human activity moved down in the distribution of altitude in the late period of history(Liao,Song,Yuan and Ming and Qing Dynasties),mainly reflected in the significant increase in the number of sites of human activities in the basins and river valleys of low altitudes.In terms of geomorphological characteristics,the sites in the study area are basically distributed around the Gurbantunggut Desert,and the landform type with the largest number of sites is the pre-mountain plain area,with 656,while there are only 6 in the desert and only 2 in the alpine areas.(3)The Holocene climate of the Junggar Basin shows a tendency of early Holocene drought,middle Holocene humidity,and late Holocene wettest.The good natural environment laid the foundation of natural geography for the expansion of human activities,the vegetation type was mainly changed from desert to desertification grassland/grassland,and then to a short desert,and then the late Holocene was mainly grassland/meadow grassland,vegetation conditions are more and more conducive to human life and development.(4)In the prehistoric period,the main influencing factors affecting the number of human activity sites were the change of humidity in the Junggar Basin and the cultural exchange of the Eurasian Steppe Silk Road.When the climate environment was good,with the increase of humidity,the grassland area expanded,the range of human activities was large,and human activities showed a trend of expanding from east to west.At the same time,the cultural exchanges between the East and the West on the Eurasian Steppe Silk Road and productivity improvement were the main reasons for the sharp rise of human activities in the early Iron Age and reached prosperity.(5)In the historical period,the main reason for the increase in human activity sites around the Junggar Basin is the expansion of transportation routes,agricultural and animal husbandry production methods,wars,government policies and other human factors,humidity has a greater impact on human activities in the natural environment,the scope of human activities is greatly limited in the dry period,human activities are more active in the humid period.