Human Diets And Its Influencing Factors During Han And Jin Periods In The Hexi Corridor And Its Adjacent Areas

The research on the man-land relationship,which is an essential part of geographicstudies,is an important way to understand the interaction mechanism between humans and environments,as well as the main content of environmental archaeology.Human subsistence in the past is a key part to link human activities and environments because that human subsistence strategy is the way for human beings to obtain food resources and the utilization of animals and plants.In the past two decades,the study on the evolution of the subsistence strategy at different spatial and temporal scales has been a hot topic in the field of geography,anthropology,and archaeology.In China,many studies on human subsistence focus on the Neolithic and Bronze Age(c.10000-2200 a BP,“a BP”:Before present(1950 AD)),while the work carried in the Paleolithic and historic periods is relatively weak.Hexi Corridor is not only the key node of the Silk Road in the historical period,but also an important region to study the cultural exchange and ethnic integration between the East and West in the historical period,which may change human subsistence strategies in this region.However,historical accounts depict social and geopolitical changes in detail,information specifying dietary and subsistence changes is murky without considering historic archaeological remains.In addition,historical record is few in the northwestern China.Therefore,the spatial pattern of human dies in the history is unclear in northwestern China,especially in the Hexi Corridor during the Han-Jin period(2152-1530 a BP)when the Silk Road was opened.However,the spatial pattern of human dies and subsistence strategy in the Hexi Corridor during the Han-Jin period is unclear.Sable isotope analysis of human bone collagen that has been powerful methods used to illustrate changes in human diets and subsistence strategies.Therefore,the study on human dietary and subsistence changes would benefit us to understand the relationship between humans and environments before and after the opening of the Silk Road.To address the above problems,it is necessary to carry out the research onsubsistence strategy in the Hexi Corridor during history periods based on archaeological materials,especially in the Han and Jin Dynasties.In this study,we collected human,animal,and plant samples from 3 Han-Jin cemetery sites in this region for archaeobotanical,zooarchaeological and isotopic analysis.We collected and dated 18 radiocarbon samples,and identified a total of 1022 animal remains to the species.Out of the identified animal bones,37 animal samples were isotopically analyzed.In addition,we collected 185 human remains(bones and teeth)from three cemeteries for stable carbon,nitrogen,hydrology,and oxygen isotope analysis.Combined our results with the published archaeological,historic,and climatic data,we systematically analyzed the change process of human subsistence strategies and their influencing factors in the Hexi Corridor and its adjacent areas during the Han and Jin Dynasites.In addition,we explored the strategies used by the Han and Jin governments and ethic integration in northwestern China based on human dietary and subsistence variation over time.The main conclusions are listed below:(1)All samples are from two stages:?2150-1750 a BP and?1750-1500 a BP,whichcoincide with Han dynasty and Jin dynasty,respectively.During the first stage,there was significantly difference between Zhangye samples and Baiyin Samples.People mainly ate C₄ foods(millets and C₄ food-fed animals)in Baiyin(mean?¹³C_human=-9.5‰),while people consumed C₄(millets and C₄ food-fed animals)and C₃(wheat,barley,rice,soybeans,and C₃ food-fed animals)foods in Zhangye(mean?¹³C_human=-16.0‰).It may be resulted by the different living environment of the two regions.(2)During the second stage,Wei and Jin dynasties,people mainly ate C₃ foods(wheat,barley,rice,soybeans,and C₃ food-fed animals)in Dunhuang(mean?¹³C_human=-18.2‰).In addition,the nitrogen isotope values of the population in Dunhuang(16.1‰)are significantly higher than the other two populations from Zhangye and Baiyin,which may be caused by the high-level intake of animal products and extreme arid environment in Dunhuang.(3)There are obvious differences in human diets between the middle Western Han Dynasty and the late Western Han-Eastern Han Dynasty in Zhangye.In the middle of the Western Han Dynasty,the ancestors ate more C₄ food(average value of?¹³C=-13.3‰),while in the late Western Han-Eastern Han Dynasty,the ancestors ate more C₃ food(average value of?¹³C=-16.1‰).It suggests that the human diets in Zhangye area during the middle Western Han Dynasty were likely to be affected by the geopolitical factors.(4)The cultural exchange and human migration between Zhangye and Baiyin during the Han dynasty is likely very limited,based on the hydrogen and oxygen isotopes of human bone collagen from these two regions.(5)We found that the dominant factors of the human dietary change in different periods are various.Around 4000 a BP,the trans-Eurasian exchange provided the abundant crops and livestock to northwestern China,which was the basic conditions for human dietary change in the following periods.The dietary change in 3700-3600 a BP from millet eaters to wheat,barley,and millet eaters was mainly triggered by climate changes.However,in the middle western Han dynasty,humans living in the Hexi Corridor and its adjacent areas briefly changed their diets influenced by the Han imperial expansion.After that,the local environment,geopolitical and exploit strategy may trigger human dietary varied in different regions.(6)By comparing the?¹⁵N values of human and animal skeletons from prehistoric,Han,and Jin sites,we found that domesticated herbivorous animal(sheep/goat,cattle)husbandry activities have played an important role in the social life of the ancestors in the Hexi Corridor around 3700 a BP since they intensified in the Hexi Corridor Area.In addition,the ancestors in the Hexi Corridor consumed more animal products since?3700 a BP.Even the population changed,domesticated herbivorous animal(sheep/goat,cattle)husbandry and animal products still played an important role in the economic life and diets during the historic period.This study provides important first-hand information for understanding thetemporal and spatial characteristics of human diet in Hexi Corridor and its adjacent areas during the Han and Jin Dynasties.It also updates our understanding of the change process and influencing factors of human subsistence strategy from the late Neolithic period to the Han and Jin Dynasties.The main performance is as follows.(1)Although the historical accounts also recorded the crops and livestock species in Hexi Corridor of Han Dynasty,their relative importance in the daily life of the ancestors is vague and information specifying dietary and subsistence changes is murky without considering historic archaeological remains.This study based on archaeological remains at least partially broke through the limitations of historical records,and quantitatively compared the role of different crops and livestock in the social life of ancestors.(2)This study found that the importance of domesticated herbivorous animal(sheep/goat,cattle)husbandry activities in the Hexi Corridor significantly increased around?3700 a BP.Even many Han farmers were moved to this area,domesticated herbivorous animal(sheep/goat,cattle)husbandry still played an important role in this area.(3)This study shows that after the Han Dynasty controlled the Hexi Corridor,the influence of geopolitical factors on the local ancestors'diets may be transient.The local ecological environment and food tradition may have more influence on human diets.This study provides important information for understanding the influence of geopolitical factors on the human subsistence of the Hexi Corridor and its adjacent areas in the Han and Jin Dynasties.In addition,this study helps to understand the evolution law of man-land relationship in the key node of the Silk Road in the context of intensified transcontinental cultural exchanges.