Kumo Xi

Omeljan Pritsak reconstructs the ethnonym underlying Middle Chinese *kʰuoH-mɑk̚-ɦei as qu(o)mâġ-ġay.

The first element qu(o)mâġ is from *quo "yellowish" plus denominal suffix *-mAk, cognate with Mongolian qumaġ "fine sands" and with Turkic qumaq and qum.

[3] As for *ɦei, Christopher Atwood (2010) proposed that it reflects an i-suffixed form of OC 胡 *gâ > hú.

[3] As for the exonym Tatabï given to Kumo Xi by Göktürks, Yury Zuev (2002) compares Tatabï to Avestan tata apo and proposes an etymology from Iranic *tata-api "falling waters", after having noted that the name of a Xī-(奚)-associated tribe Bái-Xí 白霫 (< MC *bˠæk̚-ziɪp̚) literally meant "white downpour/torrent" in Chinese, and that the Xī (奚) and Xí (霫) occupied the same area, Zhongjing (中京).

They were defeated by the Xiongnu (under Modu Chanyu), and then sought refuge in the Wuwan Mountains.

The conflict severely weakened the Kumo Xi while the Khitans were not as badly affected, resulting in their split into separate polities.

When the Tang dynasty simultaneously displayed signs of division, the Xi rose in rebellion in 847, and were subsequently and disastrously defeated by Zhang Zhongwu, the frontier commander of Lulong.

In the late ninth century AD the Khitans rose to eventually absorb the remnants of Xi people, and established the Liao dynasty in 907.