| Conflict: | Battle of the Sit River |
| Partof: | Mongol invasion of Kievan Rus' |
| Date: | 4 March 1238 |
| Place: | Modern day Yaroslavl Oblast |
| Result: | Mongol victory |
| Combatant1: | Mongol Empire |
| Combatant2: | Vladimir-Suzdal |
| Commander1: | Burundai |
| Commander2: | Yuri II |
| Strength1: | At least one tumen (10,000) of nomadic cavalry |
| Strength2: | More than 3,000, mostly infantry |
| Casualties1: | Light[1] |
| Casualties2: | Nearly Entire Force |
The Battle of the Sit River took place on 4 March 1238 between the Mongol hordes of Batu Khan and the Suzdalians under Grand Prince Yuri II of Vladimir-Suzdal during the Mongol invasion of Kievan Rus'. It was fought in the northern part of the present-day Sonkovsky District of Tver Oblast of Russia, close to the selo of Bozhonka.
After the Mongols sacked his capital of Vladimir on the Klyazma, Yuri fled across the Volga northward, to Yaroslavl, where he hastily mustered an army.[2] He and his brothers then turned back toward Vladimir in hopes of relieving the city before the Mongols took it, but they were too late. Yuri sent out a force of 3,000 men under Dorozh to scout out where the Mongols were; whereupon Dorozh returned saying that Yuri and his force was already surrounded. As he tried to muster his forces, he was attacked by the Mongol force under Burundai and fled, but was overtaken on the Sit River and died there along with his nephew, Prince Vsevolod of Yaroslavl.[3]
The battle marked the end of unified resistance against the Mongols, and inaugurated two centuries of the Mongol domination of Russia.