Kievan Rus' was composed of several principalities, ruled by the interrelated Rurikid Princes. The seat of Kiev, the most prestigious and influential of all principalities, became the subject of many rivalries between Rurikids as the most valuable prize in their quest for power, sometimes through intrigue, but often through bloody conflicts. The Golden Age of Kievan Rus' began with the reign of Vladimir the Great (Volodymyr, 980–1015), who turned Rus' toward Byzantine Christianity. During the reign of his son, Yaroslav the Wise (1019–1054), Kievan Rus' reached the zenith of its cultural development and military power. This was followed by the state's increasing fragmentation as the relative importance of regions rose again. After a final resurgence under the rule of Vladimir Monomakh (1113–1125) and his son Mstislav (1125–1132), Kievan Rus' finally disintegrated into separate principalities following Mstislav's death. The 13th century Mongol invasion devastated Kievan Rus'. Kiev was totally destroyed in 1240.^[16][17]

On the Ukrainian territory, the state of Kievan Rus' was succeeded by the principalities of Halych and Volodymyr-Volynskyi, which were merged into the state of Halych-Volynia.