Batu Khan
In the summer of 1238, Batu Khan devastated the Crimea and pacified Mordovia and the Kipchak-controlled steppe. In the winter of 1239, he sacked Chernigov and Pereyaslav. After several days of siege, the Mongols stormed Kiev in December 1240. Despite fierce resistance by Danylo of Halych, Batu Khan managed to take the two principal capitals of his land, Halych and Volodymyr-Volyns'kyi. Ruthenian principalities became vassals of the Mongol Empire.