The Byzantine authorities introduced new taxes, provoking an uprising in the Balkan Mountains in 1185. The local Bulgarians and Vlachs achieved their independence and established the Second Bulgarian Empire in coalition with the Cumans. A chieftain of the western Cuman tribes accepted Hungarian supremacy in 1227. The Hungarian expansion towards the Pontic steppes was halted by the large Mongol campaign against Eastern and Central Europe in 1241. Although the Mongols withdrew in a year, their invasion caused destruction throughout the region.