The Pechenegs were allied with Byzantium during Kurya's life (having a complicated relationship with the Rus'). Svyatoslav's Rus' had invaded the Balkan Bulgars in 967 or 968, assisting the Byzantines. However, the Slavic king's campaign had greatly exceeded the expectations of the Byzantines, under Emperor Nikephoros Phokas. Svyatoslav refused to turn over his territorial victories to the Empire (he had been paid 15,000 pounds of gold), thus the two parties dropped their alliance. After some fighting and disturbances, Svyatoslav's retreat point was besieged by the Byzantines. He surrendered and left the Balkans, relinquishing his territory while doing so.