Kuchlug, the deposed Khan of the Naiman confederation that Temüjin defeated and folded into his Mongol Empire, fled west and usurped the khanate of Qara Khitai (also known as the Western Liao, as it was originally established as remnants of the Liao dynasty). Genghis Khan decided to conquer the Qara Khitai and defeat Kuchlug, possibly to take him out of power. By this time the Mongol army was exhausted from ten years of continuous campaigning in China against the Western Xia and Jin dynasty. Therefore, Genghis sent only two tumen (20,000 soldiers) against Kuchlug, under his younger general, Jebe, known as "The Arrow".