Oasis ecosystems in drylands support local environmental functions and human well-being. Currently, these ecosystems are increasingly threatened by land desertification. Consequently, understanding the historical evolution of desertification in ancient oases within arid and semi-arid regions is essential for developing effective mitigation strategies. However, limited indicators and scarce historical records have impeded a comprehensive understanding of desertification processes in the Hexi region, northeastern the Tibetan Plateau. Nebkhas-aeolian biogeomorphological features formed through shrub-mediated trapping of sand and dust during past desertification events-represent a common desertified landscape in drylands. In this study, we systematically analyzed 32 basal-layer ages from Tamarix nebkha profiles using probability density and cumulative frequency curves. Key findings included: (1) Tamarix nebkhas in the ancient oases of the Hexi region formed in a clustered phase between 1530 and 1620 CE; (2) Tamarix nebkha formation and development in the study area coincided with cold and dry-cold climatic phases, corresponding to increased sandstorm frequency; and (3) the cold climate during the Little Ice Age of the Ming-Qing dynasties, and intensified aeolian erosion served as the primary trigger for desertification in the Hexi region. In the later stages of desertification, intensified human activities in midstream areas emerged as a critical anthropogenic driver of continued desertification expansion. These findings challenge the oversimplified view that oasis desertification is solely caused by human-induced land use changes. Moreover, this study provides compelling evidence and introduces new perspectives on desertification dynamics in the Hexi region during the Little Ice Age of the Ming-Qing dynasties in China.