Climate-driven reduction in biomass production of the Eurasian steppe coincides with nomadic migration during the first millennium CE

Although it is generally accepted today that climate and other environmental factors can affect human societies at different spatiotemporal scales, direct linkages are difficult to determine, and correlation should not be confused with causation. Here, we use a tree-ring width network of multi-millennial chronologies from inner Eurasia to reconstruct annual changes in Net Primary Productivity (NPP) back to 200 BCE. Our findings reveal that episodes of diminished NPP around the 70s–100s CE, 360s–380s CE, and 470s–560s CE likely contributed to the westward and southward migration of nomadic people from their homelands in northwestern China and Mongolia. Although prolonged multi-decadal periods of climate-induced low NPP served as tipping points for agricultural and pastoral subsistence systems, the inherent mobility of nomadic communities not only enabled them to adapt to adverse environmental conditions but also facilitated a widespread dispersal of ethnic groups.

尽管如今学界普遍认可气候与其他环境因子可在不同时空尺度上影响人类社会，但二者间的直接关联仍难以确定，且需注意切勿将相关性与因果性混为一谈。本研究依托欧亚内陆区域的千年尺度树轮宽度年表网络，重建了可追溯至公元前200年的净初级生产力（Net Primary Productivity, NPP）年际变化序列。研究结果显示，公元70-100年代、360-380年代以及470-560年代的数次NPP下降事件，可能推动了游牧族群从中国西北与蒙古的原居地向西、向南迁徙。尽管长期持续的数十年尺度气候驱动低NPP状态，成为了农牧生计系统的临界点，但游牧社群与生俱来的流动性不仅使其能够适应不利的环境条件，更推动了族群的广泛扩散。

搜集汇总

背景与挑战

背景概述

该数据集通过树木年轮数据重建了欧亚草原公元前200年至公元560年间的净初级生产力变化，揭示了气候变化导致的生物量减少与游牧民族迁徙在时间上的相关性。数据集包含一个Excel文件，记录了这些历史气候与人类迁徙模式的关键关联证据。