The De administrando imperio names "Sphendosthlabus Ingor Russiæ principis filius". The Primary Chronicle names Sviatoslav as son of Olga. His birth date is estimated on the assumption that he was a young adult when the De administrando imperio was compiled, before the death of Emperor Konstantinos VII in 959. According to the Primary Chronicle he "was but a child" in 946. At an early age, Sviatoslav´s father appears to have established him in the northern town of Gorodishche, which indicates a claim to overlordship of the northern Scandinavian settlements. The place is called "Nemogardas" in the De administrando imperio, which could be a corruption of Novgorod.
He succeeded his father as SVIATOSLAV I Grand Prince of Kiev, under the regency of his mother. Kiev was besieged by the Pechenegs in 962. Ruling alone by the mid-960s, Prince Sviatoslav launched a major attack against the Khazars in 965, using the Pechenegs as allies. He conquered the entire middle Volga area and took control of the commercial centres of Sarkel and Ityl. Sviatoslav invaded the territory of the Bulgars along the Danube in 967, having been invited to do so by Emperor Nikephoros Phokas, and established a base at Pereiaslavets on the Danube delta. It is not clear whether Pereiaslavets was the same place as Preslava, the Bulgarian capital, as Franklin & Shepard appear to assume, or a different place which appears to be the basis on which Fine writes. Zonaras records that "Borises…Bulgarorum rex" reconquered Preslav but was defeated by "Sphendosthlavus Russorum dux". Faced with the perceived threat of invasion by Sviatoslav, Emperor Ioannes Tzimisces marched into Bulgaria, captured the capital, and negotiated Sviatoslav's withdrawal. During Sviatoslav's absence in Bulgaria, the Pechenegs raided as far as Kiev. Fine points out that according to the Primary Chronicle the Bulgarians summoned the Pechenegs to attack Kiev, without help from Byzantium.
The Primary Chronicle records that, on Sviatoslav´s return journey to Kiev while crossing the Dnieper river in Spring 972, he was attacked and killed by the Pecheneg leader Kuria who reputedly made his skull into a ceremonial cup covered with gold. This represents a curious echo of the report in Paulus Diaconus according to which the skull of Alboin King of the Lombards in Pannonia was allegedly made into a drinking cup after he was defeated and killed by Cunimund King of the Gepids in 567. 1