Mongol invasion of the Khwarazmian Empire
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.
Source: Wikipedia — Mongol invasion of the Khwarazmian Empire (CC BY-SA 4.0)