Mongol invasion of Rus'
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.