Askold and Dir
He is credited by Rus' Chronicles with moving from either Staraya Ladoga () or Novgorod, and seizing power in Kiev (Kyiv) from Askold and Dir, and, by doing so, laying the foundation of the powerful state of Kievan Rus'. He also launched an attack on Constantinople, capital of the Byzantine Empire. According to East Slavic chronicles, Oleg was the supreme ruler of the Rus' from 879 to 912.