The Mongol invasion of the Khwarezmian Empire began in 1219.
The conflict followed a breakdown in relations between Genghis Khan and Khwarezmshah Muhammad II. In 1218, a Mongol merchant caravan reached the Khwarezmian city of Otrar, where its governor, Inalchuq, seized the goods and had many merchants executed as suspected spies. Genghis’s demand for punishment was rejected, and one of his envoys was killed.
Genghis responded by assembling a major army and launching a coordinated invasion in 1219. Mongol forces attacked key cities including Bukhara, Samarkand, and Urgench. Muhammad II failed to concentrate his forces, fled westward, and died in exile in 1220. His son Jalal al-Din continued resistance, but the empire was largely conquered by 1221.
A frequent mix-up is 1206, when Temüjin became Genghis Khan, and 1227, when Genghis died. The invasion’s conventional date range is 1219–1221, although its consequences—including Mongol campaigns in Persia—continued beyond those years.