What was the name of the Mongol campaign that destroyed the Khwarazmian Empire?

The Mongol campaign that destroyed the Khwarazmian Empire was the Invasion of Khwarezmia. It took place mainly from 1219 to 1221 and brought much of Central Asia and Iran under Mongol control.

The invasion followed a diplomatic and commercial crisis. In 1218, a Mongol-sponsored trade caravan was seized at Otrar, and its merchants were executed or detained. When Genghis Khan demanded redress, the Khwarazmshah Muhammad II rejected the demand and mistreated Mongol envoys. Genghis responded with a large, multi-pronged invasion.

Mongol forces captured or devastated major cities including Bukhara, Samarkand, Gurganj, Merv, Nishapur, and Herat. The Khwarazmian army was weakened by dispersed defenses and internal divisions, while Mongol mobility, intelligence, siege expertise, and coordinated attacks allowed the invaders to isolate cities one by one. Muhammad II fled and died while in retreat; his son Jalal al-Din continued resistance, but the empire did not recover. The campaign also opened the way for later Mongol domination of Persia.