奚族
The Yuwen Xianbei group Kumo Xi, who lived north of Youzhou, and the Khitan began increasing in strength. In 414, the Kumo Xi tribes sent a trade caravan to Northern Yan, then joined with the Khitan in declaring allegiance to Northern Yan, and then to Northern Wei after its destruction of Northern Yan. Thus, the Northern Wei (essentially the Tuoba Xianbei), held "de facto" rule over the entire Mongolian Plateau and the Liao River region.