Growth of power of Aisin Dynasty,submission of five groups of Khalkha Mongols to the Manchu regime,and immigration of Chahar Mongols to westward formed a conditions for Aru Mongols to immigrate to Siramuren River valley in south of the Hinggan Mountains in early 17~(th) century.

In the middle of the 17th century, in order to avoid Zhungaer tribe s assault, Heluoli belonging to Heshuote tribe and Handu belonging to Zhungaer tribe ran away to Xitao area, which was regarded as Xitao Eleuthes Mongols emergence.

Study on the Late Carboniferous and Early Permian Flora and Palaeoecology of Hulusitai Area in Inner Mongolia;