Abstract: In the paper the authors discuss the stratigraphic division of the Permian and age assignment of the Permian stratigraphic units in the Sonid Left Banner area. It is considered that the Permian in the area should comprise the Dashizhai Formation, the Zhesi Formation and the base of the Linxi Formation. The authors revise the sequence of the Permian section of the area. On the basis of an analysis of the chemical composition and REE abundances of the volcanic rocks in the Dashizhai Formation, it is considered that this formation was tectonically located on the active continental margins and that the time for the final convergence between the Sino Korean plate and Siberian plate should be middle Early Permian.