What is "kuchlug"

Kuchlug (also spelled Küchlüg, Küçlüg, Güčülüg) was a member of the Naiman tribe of western Mongolia who became the last ruler of Qara Khitai empire. The Naimans were defeated by Genghis Khan and he fled westward to the Qara Khitai, where he became an advisor. He later rebelled, usurped the throne and took control of Qara Khitai. He was killed in 1218 by the Mongols and the domain of the Qara Khitai absorbed into the rising Mongol Empire.