Oleg of Novgorod was a Varangian prince who ruled in the late 9th and early 10th centuries. He is best known for uniting the Slavic tribes and establishing the first East Slavic state, known as Kievan Rus'. Oleg is often credited with expanding trade routes and strengthening the region's economy. Oleg's reign is marked by his military campaigns, including the successful siege of Constantinople, which helped to solidify his power. He is also remembered for his diplomatic relations with neighboring states, fostering alliances that contributed to the stability of Kievan Rus'. His legacy is significant in the history of Russia and Ukraine.