Oleg, another Varangian, moves south from Novgorod to expel the Khazars from Kiev and founds Kievan Rus' about  880.

During the next thirty-five years, Oleg subdues the various East Slavic tribes.

In 907, he leads a campaign against Constantinople, and in 911 he signs a commercial treaty with the East Roman Empire as an equal partner.

The new Kievan state prospers because it controls the trade route from the Baltic Sea to the Black Sea and because it has an abundant supply of furs, wax, honey, and slaves for export.

Historians have debated the role of the Varangians in the establishment of Kievan Rus'.

Most Russian historians—especially in the Soviet era—have stressed the Slavic influence in the development of the state.

Although Slavic tribes had formed their own regional jurisdictions by 860, the Varangians accelerate the crystallization of Kievan Rus'.