Why did the Mongols fail to consolidate their conquests and create a lasting state?

Because the empire of the Mongols was very huge, besides, civil strife began between the heirs. In this connection, the empire was soon divided into separate uluses, which were constantly at enmity and rivalry among themselves. This also made it possible for the lands of north-eastern Russia to weaken the influence of the horde, and soon completely get rid of the Tatar yoke.