Abstract Chronological studies of glacial sediments from the Shishapangma and Yarlung Tsangpo River valley indicate that Quaternary glaciation on the southern Tibetan Plateau commenced at ∼0.75–0.83 Ma. However, the oldest glacial deposits in the northern plateau are dated to only ∼0.46 Ma, markedly later than the Middle Pleistocene glacial intensification evidenced in southern plateau and loess archives. Here, we report an S‐ratio record—a proxy for ferrous iron content with potential links to glacial fluctuations—obtained from a drill core in the Tengger Desert on the northern piedmont of the Qilian Mountains. This record shows a pronounced rise at ∼0.9 Ma, coincident with enhanced Fe2+‐bearing minerals in Kunlun Mountains loess and the earliest moraine deposits in the southern plateau. Collectively, these observations imply that alpine glacial activity may have intensified synchronously across the entire plateau during the Mid‐Pleistocene Transition, likely in response to global cooling and Tibetan Plateau uplift.