and had a different history.
The Varangians later assimilated into the local Slavic population and became part of the Rus' first dynasty, the Rurik Dynasty. 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 among Rurikids as the most valuable prize in their quest for power.
The Golden Age of Kievan Rus' began with the reign of Vladimir the Great (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 regional powers 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.
In the 11th and 12th centuries, constant incursions by nomadic Turkic tribes, such as the Pechenegs and the Kipchaks, caused a massive migration of Slavic populations to the safer, heavily forested regions of the north. The 13th century Mongol invasion devastated Kievan Rus'. Kiev was totally destroyed in 1240. On today's Ukrainian territory, the state of Kievan Rus' was succeeded by the principalities of Halych and Volodymyr-Volynskyi, which were merged into the state of Galicia-Volhynia.
Foreign domination
In the mid-14th century, Casimir III of Poland gained control of Galicia-Volhynia, while the heartland of Rus', including Kiev, became the territory of the Gediminas, of the Grand Duchy of Lithuania, after the Battle on the Irpen' River. Following the 1386 Union of Krewo, a dynastic union between Poland and Lithuania, much of what became northern Ukraine was ruled by the increasingly Slavicised local Lithuanian
