Battle in Wallachia

Between 1227 and 1232, Hungarian efforts to Christianise the Cumans and draw them into the kingdom, combined with Tsar Ivan Asen II's alliance with the Byzantines, led to conflict between Bulgaria and Hungary. In 1232, the Hungarians occupied western Wallachia, known as Oltenia, and proclaimed the Banate of Severin. 

They transformed the territory from a Bulgarian province into part of their kingdom. As a result of these events, the Hungarian king Béla IV began styling himself "King of Hungary, Bulgaria and Cumania".