 According to the Primary Chronicle , Oleg was a relative ( likely brother @-@ in @-@ law ) of the first ruler , Rurik , and was entrusted by Rurik to take care of both his kingdom and his young son Igor . Oleg gradually took control of the Dnieper cities , captured Kiev ( previously held by the Varangian warlords , Askold and Dir ) and finally moved his capital from Novgorod there . The new capital was a convenient place to launch a raid against <unk> ( Constantinople ) in 907 . 
