The Tokhtamysh–Timur war was fought in the 1380s and early 1390s between Tokhtamysh, khan of the Golden Horde and the warlord and conqueror Timur, founder of the Timurid Empire, in the areas of the Caucasus mountains, Turkistan and Eastern Europe. The battle between the two Mongol rulers played a key role in the decline of the Mongol power over early Russian principalities.