Svyatoslav Vsevolodovich, Grand Prince of Kiev

https://www.wikiwand.com/en/articles/Sviatoslav_I

of the Rurik Dynasty
Sviatoslav or Svyatoslav I Igorevich (Old East Slavic: Свѧтославъ Игорєвичь, romanized: Svętoslavŭ Igorevičǐ; Old Norse: Sveinald; c. 943 – 972) was Prince of Kiev from 945 until his death in 972. He is known for his persistent campaigns in the east and south, which precipitated the collapse of two great powers in Eastern Europe, Khazaria and the First Bulgarian Empire. He conquered numerous East Slavic tribes, defeated the Alans and attacked the Volga Bulgars, and at times was allied with the Pechenegs and Magyars (Hungarians).

{The Khazar empire was overrun by Svyatoslav of Kiyev around the year 969}.