Principality of Halych
Andrew II made several attempts to occupy the neighboring Principality of Halych. His son, Béla, persuaded a group of Cumans to accept Andrew II's suzerainty in 1228 and established a new march in Oltenia (known as the Banate of Szörény) in 1231. Béla IV succeeded his father in 1235. His attempt to reacquire crown lands alienated by his predecessors created a deep rift between the monarch and the lords just as the Mongols were sweeping westward across the Eurasian steppes.