The Battle of the Kalka River took place in 1223 between the forces of the Kievan Rus' and the invading Mongol Empire. The battle occurred near the Kalka River in present-day Ukraine. The Rus' princes, led by Mstislav of Galicia and Mstislav the Bold, aimed to repel the Mongol invasion but were ultimately outmaneuvered and defeated by the Mongol generals Subutai and Jebe. The defeat at the Kalka River marked a significant moment in the Mongol expansion into Eastern Europe. Following this battle, the Mongols continued their campaigns, leading to further conquests in the region. The battle is often seen as a precursor to the eventual domination of the Mongols over much of the Kievan Rus'.