Palaeomagnetic study was carried out in four Early Tertiary sections in the eastern (Dayao area) and western (Jinggu, Jiangcheng and Mengla areas) parts of the Red River fault. The study further confirms the post-Cretaceous clockwise rotation and sinistral motion of the Indochian block relative to the South China block (SCB). The results revealed a 1000 km-sinistral motion of the Indochina block along the Red River fault due to the penetraction of the Indian plate into Asia from the Early Tertiary to Miocene. This sinistral motion not only accommodated the huge crustal shortening of the Tibetan plateau, but also led to the extension tectonics in the Beibu Gulf and the opening of the South China Sea. The differential rotations of different parts in the northern Indochina block and the development of the shear zones conjugated with the Red River fault are closely related to the sinistral shearing of the Red River fault from the Early Tertiary to Miocene. These results show that extrusion is one of the main mechanism which accommodates crustal shortening during the India - Asia collision.