Batu Khan
In mid-1238, Batu Khan devastated the Crimea and pacified Mordovia. In the winter of 1239, he sacked Chernihiv and Pereiaslav. After many days of siege, the horde stormed Kiev in December 1240. Despite the resistance of Danylo of Halych, Batu Khan managed to take two of his principal cities, Halych and Volodymyr-Volynskyi. The Mongol Tartars then resolved to "reach the ultimate sea", where they could proceed no further and invaded Hungary (under Batu Khan) and Poland (under Baidar and Kaidu). Batu Khan captured Pest, and then on Christmas Day 1241, Esztergom.