Study on formation and evolution of the DatongYangyuan basin reveals that the earliest basin appeared in the region was the Jiangjunmiao basin, then the Datong basin, and the Yangyuan basin. The ancient DatongYangyuan lake did not appear until the end of the Tertiary and the beginning of the Early Pleistocene. This lake lasted about two millions years and vanished in the Late Pleistocene. Since the Cenozoic this region has experienced frequent volcanism and active tectonism. Several times of stronger earthquake have happened in recent decades.