Sviatoslav I of Kiev (East Slavic: Святослав, ca. 942 – 972), was the warrior prince (or konung) of Kievan Rus'. The son of Igor of Kiev and Olga, Sviatoslav is famous for his incessant campaigns in the east and south, which precipitated the collapse of two great powers of Eastern Europe — Khazaria and the First Bulgarian Empire; he also subdued the Volga Bulgars, the Alans, and numerous East Slavic tribes, and at times was allied with the Pechenegs and Magyars. His decade-long reign over Rus was marked by rapid expansion into the Volga River valley, the Pontic steppe and the Balkans. By the end of his short life, Sviatoslav carved out for himself the largest state in Europe, eventually moving his capital from Kiev to Pereyaslavets on the Danube in 969. In contrast with his mother's conversion to Christianity, Sviatoslav remained a staunch pagan all of his life. Due to his abrupt death in combat, Sviatoslav's conquests, for the most part, were not consolidated into a functioning empire, while his failure to establish a stable succession led to civil war among his successors.