It was a heavy morale and military blow to the Principality of Galicia–Volhynia, which was forced to submit to Mongol suzerainty, and allowed Batu Khan to proceed westward into Central Europe.

[9] The Smolensk prince Rostislav II Mstislavich seized the opportunity to claim Kiev for himself, but was in turn soon driven out by Daniel of Galicia-Volhynia (Danylo Romanovych).

Batu Khan destroyed the forces of the Rus vassals, the Chorni Klobuky,[12] who were on their way to relieve Kiev, and the entire Mongol army camped outside the city gates, joining Möngke's troops.

[citation needed] Scholar Alexander Maiorov (2016) compared all the dates in the surviving records of the events, concluding that the siege of Kiev lasted just nine days, from 28 November to 6 December 1240.

[5] After their victory at Kiev, the Mongols forced both Galicia and Volhynia to submit to Batu Khan's suzerainty, and they were free to advance westward into Hungary and Poland.

[15] All the major reigning Rus' princes eventually made the journey to Sarai, the capital city of Batu Khan's newly established Golden Horde state.

[15] However, Michael refused to "purify himself by walking between two fires and to kowtow before an idol of Chingis Khan"; this offence reportedly angered Batu, who had him executed in September 1246.

[16] Although the 1240 siege of Kiev has been described in nearly every Rus' chronicle written after the events, they vary widely in the details, contradict each other and have conflicting dates as to when it happened exactly.