The Kievan Rus Period

The Kievan Rus Period, roughly 882 to 1240, was the era of Kievan Rus, a loose federation of East Slavic and Finnic peoples centered on Kiev and founded, according to tradition, by the Varangian prince Oleg, that is regarded as the common ancestor state of Russia, Ukraine and Belarus. Its ruler Vladimir the Great adopted Orthodox Christianity from Byzantium in 988, a decision that shaped the religious and cultural trajectory of the East Slavic world for the following millennium, while Kiev itself grew into a major trading center linking Scandinavia to the Byzantine Empire along the Dnieper River trade routes. Kievan Rus fragmented into competing principalities from the twelfth century and was finally shattered by the Mongol invasion of 1237 to 1240, which destroyed Kiev and subjected most of the Rus principalities to Mongol overlordship.