Rus state finally disintegrated under the pressure of the Mongol invasion of 1237–1242. Its successor principalities started paying tribute to the Golden Horde (the so-called Tatar Yoke). From the mid-13th to mid-15th centuries, princes of North-Eastern Rus received a "yarlyk" (a special edict of Golden Horde khan). The issuing of yarlyk on governing of Rus finalized the establishment of the title of Grand Prince of Vladimir and the transfer of power from Kiev to Vladimir. As many factions strove for power, the principality rapidly disintegrated into tiny states. All of them nominally acknowledged the suzerainty of the Grand Prince, but his effective authority became progressively weaker. By the end of the century, only three cities – Moscow, Tver, and Nizhny Novgorod – still contended for the title of Grand Prince of Vladimir. Once installed, however, they chose to remain in their own cities rather than moving to Vladimir.