Loess—paleosol sequences have many characteristics which are beneficial to research the paleoclimate, such as the good continuity, long span of time, and so on. It has been regarded as one of the three archives for researching the palaeoenvironment. Red clay is attested to be eolian deposits, just like the loess—paleosol sequence. The bottom ages of the red clay sections are about ~8Ma in the eastern Liupan Mountain, while they are 25~22 Ma in its western part. Basing on the analysis of the provenances, geomorphology of the migration way of the eolian, and tectonics in the northern Qinghai—Xizang(Tibetan) Plateau, the writers draw the following conclusions: ① widespread arid zones in Asian interior since the late Oligocene—early Miocene are mainly resulted from the uplifted Tibetan Plateau which obstructed the southwest monsoon and the retreat of the Para-tethys. ②The westerly wind and funneling gave rise to the deposition of the red-clay in the western part of the Liupan Mountain. The cause of the red clay deposition did not appear in the eastern part of the Liupan Mountain is the winter monsoon could not pass through the westerly wind “wall” and the high mountains. ③ Onset of the red clay deposition in the eastern part of the Liupan Mountain since ~ 8Ma suggests that the Mongolia Siberian high pressure strength has reached present level. It also indicates that the Tibetan Plateau has uplifted outward and upward before the late Miocene.