6000~2000a B.P.丝绸之路国内段人类活动的时空格局与影响因素研究

SPATIO-TEMPORAL PATTERN OF HUMAN ACTIVITIES AND THEIR INFLUENCING FACTORS ALONG THE ANCIENT SILK ROAD IN NORTHWEST CHINA FROM 6000 A B.P. TO 2000 A B.P.

丝绸之路国内段主要包括丝路东段(西安至敦煌)和丝路中段(新疆地区),是丝路文明演化的主体地段,也是古丝绸之路开通之前跨大陆交流的关键地段。丝路东段和中段降水的时空格局存在显著差异,人类活动历史也有明显区别。然而,6000 a B.P.("B.P."为"距今(1950 A.D.)年")左右丝路东段农业强化之后,至古丝绸之路开通(约2000 a B.P.)该地区人地关系演化的时空过程和动力尚不清晰。文章通过总结丝绸之路国内段沿线地区已发表的碳十四测年与植物考古资料,结合丝路东段和中段古气候记录的对比分析,探讨了该地区6000~2000 a B.P.人类活动的时空格局和影响因素。结果显示,丝路东段6000~4000 a B.P.的粟黍农业发展促进了农业人群的广泛扩张,人类活动强度还受到降水变化的影响;4000~2000 a B.P.该地区人类活动强度的主要影响因素是跨大陆交流带来的生业模式多样化、生产工具的革新和地缘政治形势变化,而不是气候变化。丝路中段6000~4000 a B.P.人类活动强度很低,4000~2000 a B.P.人类活动强度显著提升,与降水变化呈现较为一致的特征,青铜时代的降温则可能导致人类定居空间的南向移动。本研究显示丝绸之路国内段不同时间与空间人地关系演变过程和主导因素存在显著差异,有助于理解丝绸之路开通之前其核心区的人与环境相互作用变化过程和机制。

The areas along the Ancient Silk Road(ASR)in Northwest China encompass the eastern section of the ASR(from Xi'an to Dunhuang,EASR)and the middle section of the ASR(Xinjiang region,MASR),which are the primary focus for the evolution of the civilizations along the ASR,as well as transcontinental exchanges in the late prehistoric periods.The spatial-temporal patterns of precipitation and human activities in EASR and MASR appear significantly different,especially between 6000~2000 a B.P.(Before Present,defined as 1950 A.D.),when farming groups began to intensively settled in northwest China.However,the trajectory and influencing factors for the evolution of human-land relation in the areas along the ASR in northwest China remain unclear.In this paper,we summarize the legacy data of radiocarbon dating,archaeobotanical analysis and paleoclimatic studies in EASR and MASR,to explore the spatial-temporal variation of human activities and the underlying impetus.A total number of 1272 published radiocarbon dates covering 6000~2000 a B.P.from 295 sites along the ASR in northwest China are revisited,including 910(236 sites)in EASR and 362(59 sites)in MASR.Furthermore,379156(150 sites)and 12032(15 sites)identified crop remains in EASR and MASR are analysed,respectively.The results reveal critical difference in the spatial-temporal patterns of human settlement in EASR and MASR during 6000~2000 a B.P.In EASR,the intensity of human settlement virtually increased between ca.6000~4800 a B.P.,dropped between ca.4800~4500 a B.P.,then increased again around 4500 a B.P.and finally reached the peak between ca.4200~3800 a B.P.,in particular,it was relatively high between ca.3800~2800 a B.P.with small fluctuations.The intensity of human settlement in EASR during ca.2800~2000 a B.P.is needed to be examined in future research,due to the appearance of inscriptions.In MASR,the intensity of human activities was low between 6000~4000 a B.P.but increased markedly around 4000 a B.P.and remained a high level between 4000~2000 a B.P.We propose that the intensification and development of rain-fed agriculture promoted the expansion of farming groups and human settlement intensity in EASR between 6000~4000 a B.P.In this light,precipitation variation becomes another important influencing factor.However,the diversification of livelihoods derived from prehistoric trans-Eurasia exchange,technological innovation and geopolitical interaction,instead of climate change,triggered the spatial-temporal variation of human activities in that area during 4000~2000 a B.P.Precipitation in MASR during 4000~2000 a B.P.was obviously higher than 6000~4000 a B.P.,which might have facilitated intensive human settlement in the area since the Bronze Age.The notable decline in temperature during the 4^(th) Millennium might be responsible for the southward movement of people in MASR during Bronze Age.This study suggests that the dominant factors for human-land relation evolution were different in the eastern and middle parts of the ASR between 6000~2000 a B.P.,which advances our understanding of the process and mechanism of human-environment interaction in these areas before the rise of ASR.