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Inland Asian aridification is threatening the global ecological system under continued global warming, requiring a full understanding of its forcing mechanisms. Past geological studies in this region focus mainly on initiation timing and million-year timescale variations in aridification. Few studies address the relationship between aridification and insolation forcing. Here we present a paleomagnetic and evaporite mineralogic study of the 476-m-long Huatugou (HTG) section (ca. 3.9 to 2.1 Ma) from the western Qaidam Basin. The results show that the drying of this part of the basin began by at least 3.9 Ma. Furthermore, we show that the relative content variation of evaporite minerals was dominated by 100-kyr cyclicity during the Pliocene. This is consistent with the result from the Xining area during the late Eocene. These results suggest that mid-latitude lacustrine evaporite minerals in semi-arid to arid regions are particularly sensitive to eccentricity forcing, improving understanding of aridification forcing at orbital timescales.