The human-environment relationship under synergy between westerly winds and monsoon in the middle reaches of Yarlung Tsangpo River

The middle reaches of the Yarlung Tsangpo, with its relatively favorable environmental conditions, is a key area for prehistoric human activity on the Xizang Plateau. This study analyzes two aeolian sediment profiles (RM and CGG) using geochemical elements, grain size, magnetic susceptibility to evaluate soil formation intensity and discuss the corresponding climatic conditions. Probability density functions of derived from 33 paleosol age records were used to reconstruct spatiotemporal evolution. The results were compared with the paleo-climate record. It was found that the development of paleosol development may have been influenced by both Westerlies and Indian summer monsoon (ISM): During the early Holocene (10.5–6.8 ka), paleosol development was weak, primarily influenced by the ISM, exhibiting an alternating pattern of ’main stream-tributary-main stream. In the mid-Holocene (6.8–3.3 ka), when the Westerlies were dominant, paleosol development intensified alone the main stream, coinciding with the agricultural settlement. However, during the Late-Holocene (after 3.3 ka), paleosol development weakened in response to a combined decline in the ISM and Westerlies influence, signaling a shift toward a harsher climate. Nonetheless, the renewed development of tributary paleosols, during 2-3 ka BP, appears to have supported the restructuring of subsistence strategies into a barley-dominated agro-pastoral system. These findings provide insights into human-environment interactions of middle reaches of the Yarlung Tsangpo.