After the enormous destruction wreaked by the Mongol invasion of Kievan Rus' in 1239–41, the King of Rus' Danylo Romanovych was forced to pledge allegiance to Batu Khan of the Golden Horde in 1246. He strove, however, to rid his realm of the Mongol yoke by attempting, unsuccessfully, to establish military alliances with other European rulers. The Polish conquest of the kingdom in 1349 ended its vassalage to the Golden Horde.