The sedimentary characteristics, grain-size distribution, geochemical composition and surface characteristics of quartz grains, together with palaeoenvironmental reconnaissance, all point to an aeolian origin for the intercalated siltstone beds in the Plio-Pleistocene Artux and Xiyu Formations along the southern margins of the Tarim Basin, indicating that loess deposition in the region started, at least, in the Early Pliocene. Loess deposition in the southern Tarim Basin was a response to the global deterioration, which might be attributed to the uplift of the Tibetan Plateau. The sedimentary characteristics, grain-size distribution, geochemical composition and surface characteristics of quartz grains, together with palaeoenvironmental reconnaissance, all point to an aeolian origin for the intercalated siltstone beds in the Plio-Pleistocene Artux and Xiyu Formations along the southern margins of the Tarim Basin, indicating that loess deposition in the region started, at least, in the Early Pliocene. Loess deposition in the southern Tarim Basin was a response to the global deterioration, which might be attributed to the uplift of the Tibetan Plateau.