Oleg was the ruler of
Drelinia, a region which is today in the western
Ukraine.
He was the son of
Sviatoslav I of Kiev. Sviatoslav split up his domains, and gave Drevlinia to Oleg. Oleg and his brother
Yaropolk went to war after their father's death. This war eventually resulted in Oleg's defeat and the reunification of his lands with Kiev.