Mongol conquest of the Qara Khitai in the context of "Mongol conquest of Khwarezmia"

Between 1219 and 1221, the Mongol forces under Genghis Khan invaded the lands of the Khwarazmian Empire in Central Asia. The campaign, which followed the annexation of the Qara Khitai Khanate, saw widespread devastation and atrocities. The invasion marked the completion of the Mongol conquest of Central Asia, and began the Mongol conquest of Persia.

Both belligerents, although large, had been formed recently: the Khwarazmian dynasty had expanded from their homeland to replace the Seljuk Empire in the late 1100s and early 1200s; nearly simultaneously, Genghis Khan had unified the Mongolic peoples and conquered the Western Xia dynasty. Although relations were initially cordial, Genghis was angered by a series of diplomatic provocations. When a senior Mongol diplomat was executed by Khwarazmshah Muhammed II, the Khan mobilized his forces, estimated to be between 90,000 and 200,000 men, and invaded. The Shah's forces were widely dispersed and probably outnumbered—realizing his disadvantage, he decided to garrison his cities individually to bog the Mongols down. However, through excellent organization and planning, the Mongols were able to isolate and conquer the Transoxianan cities of Bukhara, Samarkand, and Gurganj. Genghis and his youngest son Tolui then laid waste to Khorasan, destroying Herat, Nishapur, and Merv, three of the largest cities in the world. Meanwhile, Muhammed II was forced into flight by the forces of Mongol generals Subutai and Jebe; unable to reach any bastions of support, he died destitute on an island in the Caspian Sea. His son and heir Jalal-al Din managed to mobilize substantial forces, defeating a Mongol general at the Battle of Parwan, but these were crushed by Genghis at the Battle of the Indus a few months later.

The Qara Khitai, or Kara Khitai (simplified Chinese: 哈剌契丹; traditional Chinese: 喀喇契丹; pinyin: Kālā Qìdān or Chinese: 黑契丹; pinyin: Hēi Qìdān; lit. 'Black Khitan'), also known as the Western Liao (Chinese: 西遼; pinyin: Xī Liáo), officially the Great Liao (Chinese: 大遼; pinyin: Dà Liáo), was a dynastic regime based in Central Asia ruled by the Yelü clan of the Khitan people. Being a rump state of the Khitan-led Liao dynasty, Western Liao was culturally Sinicized to a large extent, especially among the elites consisting of Liao refugees.

The dynasty was founded by Yelü Dashi (Emperor Dezong), who led the remnants of the Liao dynasty from Manchuria to Central Asia after fleeing from the Jurchen-led Jin dynasty conquest of northern China. The empire was usurped by the Naimans under Kuchlug in 1211; traditional Chinese, Persian, and Arab sources consider the usurpation to be the end of the dynasty, even though the empire would not fall until the Mongol conquest in 1218. Some remnants of the Qara Khitai would form the Qutlugh-Khanid dynasty in southern Iran.

The Qutlugh-Khanids (Persian: قراختاییان کرمان, otherwise known as the Qutlugh-Khanid dynasty, Kirmanid dynasty, or infrequently as the Later Western Liao;后西辽) was a culturally Persianate dynasty of ethnic Khitan origin that ruled over Kirman (in present-day Kerman Province, Iran) from 1222 to 1306.

It was founded by Buraq Hajib, who emigrated from the Qara Khitai (Western Liao dynasty) during the collapse of the realm. Originally an independent entity, the Qutlugh-Khanid dynasty subsequently ruled as vassals of the Khwarazmian dynasty, the Mongol Empire and the Ilkhanate. The dynasty was removed from power by the Ilkhanid ruler Öljaitü, who appointed Nasir al-Din Muhammad ibn Burhan as governor of Kirman.