In alliance with the Bulgarians and Vlachs, the Cumans are believed to have played a significant role in the uprising led by brothers Asen and Peter of Tarnovo, resulting in victory over Byzantium and the restoration of Bulgaria's independence in 1185. István Vásáry states that without the active participation of the Cumans, the Vlakho-Bulgarian rebels could never have gained the upper hand over the Byzantines, and ultimately without the military support of the Cumans, the process of Bulgarian restoration could never have been realised. The Cuman participation in the creation of the Second Bulgarian Empire in 1185 and thereafter brought about basic changes in the political and ethnic sphere of Bulgaria and the Balkans. The Cumans were allies in the Bulgarian–Latin Wars with emperor Kaloyan of Bulgaria.