Historical human activities accelerated climate-driven desertification in China's Mu Us Desert

China's Mu Us Desert, located in an energy-rich strategic base of the northwestern Loess Plateau, has acted as a crucial agro-pastoral transition zone for thousands of years. However, the area experienced notable climate and environmental change from 221 BCE to CE 907 (1128 years), which may have profoundly affected its landscape evolution up to modern times. To explore this process and associated driving mechanisms, we conducted a comprehensive study based on a dataset of 882 human archaeological sites (HASs), historical documents, and related environmental data of the Mu Us Desert and its surrounding area (MUDISA). We found that the MUDISA experienced large-scale immigration and an agricultural boom (790 HASs) during the Qin and Han dynasties (221 BCE-CE 220). This coincided with an ecologically favorable environment and may have potentially disturbed the desert's eco-environmental equilibrium. Coinciding with the deteriorating natural conditions, the MUDISA's animal husbandry replaced agriculture as the dominant subsistence economy during the era of disunity (CE 220-581, 33 HASs) and during the Sui and Tang dynasties (CE 581-907, 59 HASs). Although natural and political-economic factors together caused a sharp decline in number and scattering for HASs in the desert, people and livestock were widely distributed and maintained a high population level. This situation, coupled with the dry climate and fragile geographical environment, may have significantly accelerated the climate-driven desertification process from CE 220 to CE 907. This study highlights the long-term human-nature relationship and its impact on historical desertification in the Mu Us Desert, and may shed new light on historical environmental change in arid and/or semi-arid areas in northwest China and globally. (C) 2019 Elsevier B.V. All rights reserved.