The Battle of the Kalka River takes place on May 31, 1223, between the Mongol Empire (led by Jebe and Subutai) and Kiev, Galich, and several other Rus' principalities and the Cumans, under the command of Mstislav the Bold and Mstislav III of Kiev.

The battle is fought on the banks of the Kalka River and ends in a decisive Mongol victory.Following the Mongol invasion of Central Asia and the subsequent collapse of the Khwarezmian Empire, a Mongol force under the command of generals Jebe and Subutai advances into Iraq-i Ajam.

Jebe requests permission from the Mongol leader, Genghis Khan, to continue his conquests for a few years before returning to the main army via the Caucasus.

While waiting for Genghis Khan's reply, the duo sets out on a raid in which they attack Georgia and kill its king.

Genghis Khan grants the duo permission to undertake their expedition, and after making their way through the Caucasus, they defeat a coalition of Caucasian tribes before defeating the Cumans.

The Cuman Khan flees to the court of his son-in-law, Prince Mstislav the Bold of Galich, who he convinces to help fight the Mongols.

Mstislav the Bold forms an alliance of the Rus' princes including Mstislav III of Kiev.The combined Rus' army, at first, defeats the Mongol rearguard.

For several days, the Rus' pursue the Mongols but become spread out over a large distance.

The Mongols stop and assume battle formation on the banks of the Kalka River.

Mstislav the Bold, with his Cuman allies, attacks the Mongols without waiting for the rest of the Rus' army and is defeated.

In the ensuing confusion, several other Rus' princes are defeated, and Mstislav of Kiev is forced to retreat to a fortified camp.

After holding for three days, he surrenders in return for a promise of safe conduct for himself and his men.

Once they surrender, however, the Mongols slaughter the men and execute Mstislav of Kiev.

Mstislav the Bold escapes, and the Mongols return to Asia, where they join Genghis Khan.