In 1226, his father entrusted him with the government of Transylvania where he assisted the missionary work of the Blackfriars among the Cuman tribes who settled down in the territories west of the Dniester River.
In 1226, his father entrusted him with the government of Transylvania with the title of duke. Here Béla assisted the missionary work of the Blackfriars among the Cuman tribes who settled down in the territories west of the Dniester River.