Answer
Daniil Romanovich, Prince of Halych, Boleslaw the Chaste, Duke of Cracow, and other Ruthenian and Polish princes were included in Béla IV's defensive alliance against the Mongols. Béla IV, the King of Hungary, had been defeated by the Mongols in 1241. He then formed an alliance with the Ruthenian and Polish princes in order to protect his kingdom from further Mongol invasions.