Kaloyan was the younger brother of Theodor and Asen, noted as the instigators of the uprising of the Bulgarians and Vlachs (the latter being Balkan Romanians) against the Byzantine Empire in 1185. Theodor was crowned emperor and adopted the name Peter in 1185. Asen became Peter's co-ruler before 1190. They secured the independence of their realm with the assistance of Cuman warriors from the Pontic steppes.