What was the name of the battle where Jalal ad-Din defeated the Mongols in 1221?

The battle where Jalal ad-Din defeated the Mongols in 1221 was the Battle of Parwan. It took place near Parwan, north of Kabul in present-day Afghanistan, during the Mongol invasion of the Khwarezmian Empire.

Jalal ad-Din Mangburni had gathered Khwarezmian loyalists, Afghan warriors, and Turkic troops after the collapse of his father's empire. Genghis Khan sent an army commanded by Shigi Qutuqu to eliminate him. The battle lasted two days—or three, according to some accounts—and the narrow terrain limited the Mongol cavalry's usual mobility.

Jalal ad-Din used disciplined archery and carefully timed attacks to break the Mongol force. The victory was a major shock because Mongol armies had rarely suffered such a serious defeat against a Muslim opponent. It also encouraged rebellions in cities that had submitted to Mongol rule.

The triumph proved temporary. A dispute over the division of captured spoils caused important allies to desert Jalal ad-Din, weakening his army. Genghis Khan then pursued him and defeated him at the Battle of the Indus later in 1221.