When the Tartars first saw iron, and their strongest warriors failed to bend it, they thought there must be a substance under the surface. So they called it _timur_, which means something stuffed or filled.[608] It soon became a custom to name their great leaders Timur. But even among primitive peoples the qualities of leadership have not necessarily included purely physical strength. Many Samsons among the Tartars received the distinction of being called Iron. None of them made an indelible mark upon the history of the world, save the great Timur, who had his left arm and left leg partially paralysed.[609] At the height of his career, when his hordes marched against Bagdad, he was too weak to sit upon a horse, and was carried in a litter.[610] Timur claimed descent from the grand vizier of Djagataï, son and successor of Djenghiz Khan. He came to the throne of Khorassan, with residence at Samarkand, in 1369. In thirty years, while Murad and Bayezid were winning an empire in the Balkan peninsula, Timur became master of the greater part of the Moslem world. Persia, Armenia, the upper valleys of the Tigris and Euphrates, the steppes between the Caspian and Black Seas, Russia from the Volga to the Don and Dnieper, Mesopotamia, the coasts of the Indian Ocean and the Persian Gulf, and western and northern India was his path of conquest. After he had captured Sivas, Bayezid had not been able to curb the altogether natural impulse that led him into the valley of the Euphrates. In his way stood Kara-Yussuf, a Turcoman prince of Kharput, who was to be, after Timur’s death, the founder of the famous dynasty of the Black Sheep.[611] In 1399, Bayezid had put his son Soleiman, assisted by several of his ablest generals, in charge of an advance movement to the east. Sivas was the base of operations. Kara-Yussuf, who had a claim upon Timur’s protection because he had guided him on his first expedition into Armenia, appealed to the Tartar court. Before Timur could remonstrate, Kara-Yussuf was captured by the Osmanlis. When Timur learned this, his anger was for the first time directed specifically against Bayezid. There were old complaints against Bayezid. The refugee emirs had not lived at his court for years without impressing upon Timur their woes and the injustice that had been done to them. But Timur was busy with other plans and other conquests. Bayezid’s former activities had not directly touched him.