Sviatoslav I was the son of Igor, former Grand Prince of the Rus, and his wife Olga, who had served as regent during Sviatoslav's youth. When he took over from his mother between 962 and 965, Olga stayed in their capital of Kiev and kept things running smoothly while her son went out to conquer; he subjugated tribes to the east and south of Kievan Russia and received their tribute, bringing the entire Volga River down to the Caspian Sea under Russian control. After Olga died in 969, he set up his sons as deputies in different cities: Yaropolk in Kiev, Oleg among the Derevlians, and Vladimir in Novgorod. He also attacked the Bulgars and proposed to move his capital city from Kiev to Pereyaslavets on the Danube River, much father west. (This did not happen, though, as he had to abandon the attacks on the Bulgars and go home to relieve Kiev from a siege by the Pechenegs, a people who lived on the other side of the southeastern tribes now under Sviatoslav's rule.)

During his attacks on the Bulgars, Sviatoslav's expansion became a threat to the Byzantine Empire which would be the likely next target. The Byzantines attacked, but at first the Russians were able to defeat them and advance into Byzantine territory to threaten Constantinople. After a rebellion in farther-away parts of the Byzantine Empire was put down, though, the emperor/military leader John Tzimisces was able to send in more troops against the Russians and beat them back. Peace was made in July 971, with Sviatoslav promising to leave the Balkans and the Empire alone. On his way, home, though, Sviatoslav was captured by the Pechenegs and killed in the spring of 972. There was civil war between his sons, with Oleg being killed and the oldest, Yaropolk I, coming out on top at first.