Tukush obtained investiture at Bagdad from the Kalif, and Persia passed from one line of Turkish tyrants to another. Mohammed, who succeeded his father Tukush, in 1200, seized the provinces of Balkh and Herat and made himself lord of Khorassan. Soon after this Mazanderan and Kerman passed under his power and direction. Mohammed now planned to shake off the authority of the Gurkhan of Kara Kitai, to whom he, and three of his predecessors, had paid yearly tribute. Besides he was urged to this step by Osman, Khan of Samarkand and Transoxiana, who, being also a vassal of the Gurkhan, endured with vexation the insolence of agents who took the tribute in his provinces. Osman promised to recognize Mohammed as his suzerain, and pay the same tribute that he had paid to the Gurkhan. The Shah accepted this offer with gladness; he merely waited for a pretext, which appeared very quickly: An official came to receive the yearly tribute, and seated himself at the Shah’s side, the usual place in such cases, though it seemed now that he did so somewhat boldly. Mohammed’s pride, increased much by recent victory over Kipchaks living north of the Caspian, would endure this no longer, so in rage he commanded to cut down the agent and hack him to pieces. After this act Mohammed invaded the lands of the Gurkhan immediately (1208), but was defeated in the ensuing battle, and captured with one of his officers. The officer had the wit to declare that the Shah, whose person was unknown in those regions, was a slave of his. In a short time the amount of ransom for the officer was settled; he offered to send his slave to get the sum needed. This offer was taken and an escort sent with the slave to protect him. Thus did Mohammed return in servile guise to his dominions, where reports of his death had preceded him. In Taberistan his brother, Ali Shir, had proclaimed his own rule, and his uncle, the governor of Herat, was taking sovereign power in that region. The following year Mohammed and Osman, the Samarkand ruler, made a second attack on the Gurkhan. Crossing the Syr Darya at Tenakit, they met their opponents, commanded by Tanigu, and won a victory. They conquered a part of the country as far as Uzkend, and instated a governor. The news of this sudden success caused immense joy in the Kwaresmian Empire. Embassies were sent by neighboring princes to congratulate the victor. After his name on the shield was added “Shadow of God upon earth.” People wished to add also “Second Alexander,” but he preferred the name Sindjar, since the Seljuk prince Sindjar had reigned forty-one years successfully. After his return the Shah gave his daughter in marriage to Osman, and the Gurkhan’s lieutenant in Samarkand was replaced by a Kwaresmian agent. Soon, however, Osman was so dissatisfied with this agent that he gave back his allegiance to the Gurkhan, and killed the Kwaresmians in his capital.