
The arrival of the Cumans in the Lower Danube region was first recorded in 1055.[43] Cuman groups assisted the rebelling Bulgarians and Vlachs against the Byzantines between 1186 and 1197.[44] A coalition of Rus' princes and Cuman tribes suffered a sound defeat by the Mongols in the Battle of the Kalka River in 1223.[45] Shortly thereafter Boricius, a Cuman chieftain,[46] accepted baptism and the supremacy of the king of Hungary.[47]