Mongol conquest of the Qara Khitai

Battle context

The Mongol conquest of the Qara Khitai in 1218 removed one of the remaining powers of Central Asia and brought the Mongol Empire into direct territorial contact with the Khwarazmian Empire, setting the stage for the invasion that followed in 1219. The Qara Khitai had already been weakened before the campaign began: sustained conflict with the Khwarazmian Empire and the internal usurpation of power by the Naiman prince Kuchlug had eroded the state's cohesion. The immediate trigger for Mongol intervention was Kuchlug's siege of Almaliq, a city belonging to the Karluk vassals of the Mongol Empire, and his killing of their ruler Ozar, who held a marriage connection to Genghis Khan. Genghis Khan dispatched a force under Jebe and Barchuk in response. Kuchlug's defeat at Balasagun was compounded by popular rebellions against his unpopular rule, which forced him to flee southward into what is now Afghanistan, where he was captured by hunters and handed over to the Mongols, who executed him. The elimination of the Qara Khitai thus resulted as much from internal collapse as from direct military defeat, and its chief strategic consequence for the Mongol invasion of Central Asia was the creation of a shared frontier with the Khwarazmian Empire.