The state finally disintegrated under the pressure of the Mongol invasion of Rus', fragmenting it into successor principalities who paid tribute to the Golden Horde (the so-called Tatar Yoke). In the late 15th century, the Muscovite Grand Dukes began taking over former Kievan territories and proclaimed themselves the sole legal successors of the Kievan principality according to the protocols of the medieval theory of translatio imperii.
On the western periphery, Kievan Rus' was succeeded by the Principality of Galicia-Volhynia. Later, as these territories, now part of modern central Ukraine and Belarus, fell to the Gediminids, the powerful, largely Ruthenized Grand Duchy of Lithuania drew heavily on Rus' cultural and legal traditions. From 1398 until the Union of Lublin in 1569 its full name was the Grand Duchy of Lithuania, Ruthenia and Samogitia. Due to the fact of the economic and cultural core of Rus' being located on the territory of modern Ukraine, Ukrainian historians and scholars consider Kievan Rus' to be a founding Ukrainian state.
On the north-eastern periphery of Kievan Rus', traditions were adapted in the Vladimir-Suzdal Principality that gradually gravitated towards Moscow. To the very north, the Novgorod and Pskov Feudal Republics were less autocratic than Vladimir-Suzdal-Moscow until they were absorbed by the Grand Duchy of Moscow. Russian historians consider Kievan Rus' the first period of Russian history.