The Kumo Xi (called the Xi since the Sui dynasty (581-618) are a Mongolic steppe people located in current Manchuria (northeast China) from 207 to 907 CE.

After the death of their ancestor Tadun in 207 they are no longer called Wuhuan but join the Khitan Xianbei in submitting to the Yuwen Xianbei.

Their history is widely linked to the more famous Khitan.

During their history, the Kumo Xi engages in conflict with numerous Chinese dynasties and with the Khitans, eventually suffering a series of disastrous defeats to Chinese armies and coming under the domination of the Khitans.

In 1007, the Kumo Xi are completely assimilated into the Khitan Liao Dynasty.