The basin group in the east part of Nei Monggol are Middle Cenozoic fault-depressed basins developed on Hercynian basement. The landform of the basins is the result of multiple superimposition of structures. The basin's structural evolution underwent five different evolution stages such as stretch-depressed stage in Early-Middle Jurassic and Early Cretaceous Periods

the reversion stage in late Early Jurassic and late Early Cretaceous and the complete uplift stage since Late Cretaceous. The formation of the Early-Mildle Jurassic fault-depressed basin was related to the differential movement of the East Asian Plate; the reversion of the structures was the result of the close of Monggol-Okhotsk Ocean and the structures of oceanic plate

the Early Cretaceous fault-depressed basin was derived from back-arc deep-seated action caused by the subduction of the Pacific tectonic tract; the late Early Cretaccous basin reversion might beresulted from sinistral strike-slip of East China.