Timur was the most powerful [[ Central Asia]] n ruler since [[Genghis Khan]]. By long and relentless fighting, he sought to rebuild the Mongol Empire of his ancestors.<ref>Beatrice Forbes Manz, "Temür and the Problem of a Conqueror's Legacy," ''Journal of the Royal Asiatic Society'', Third Series, Vol. 8, No. 1 (Apr., 1998), 25; "In his formal correspondance Temur continued throughout his life as the restorer of Chinggisid rights. He even justified his Iranian, Mamluk and Ottoman campaigns as a reimposition of legitimate Mongol control over lands taken by usurpers...".</ref><ref>Michal Biran, "The Chaghadaids and Islam: The Conversion of Tarmashirin Khan (1331-34)," ''Journal of American Oriental Society'', Vol. 122, No. 4 (Oct. - Dec., 2002), 751; "Temur, a non-Chinggisid, tried to build a double legitimacy based on his role as both guardian and restorer of the Mongol Empire.".</ref>
Timur had conquered [[Georgia (country)|Georgia]] and [[Azerbaijan]] in 1390, expanding his empire to the borders of the Ottoman Empire. The two powers soon came into direct conflict. Bayezid demanded tribute from one of the [[Anatolian Beyliks]] who had pledged loyalty to Timur and threatened to invade. Timur interpreted this action as an insult to himself and in 1400 sacked the Ottoman city of Sebaste (modern [[Sivas, Turkey|Sivas]]). Beyazid was stung into furious action and when Timur invaded [[Anatolia]] from the east, Bayezid summoned his forces and confronted Timur's forces near Ankara. The conflict, overall, was the culmination of years of insulting letters exchanged between Timur and Bayezid.