Tekish[337] was, in A.H. 588 (1192), firmly settled on the throne of Khwārazm. Confident in the devotion of an army which he had led to victory, he grew ambitious and forgot the obligations under which the Kara-Khitāy had placed him. He incurred the wrath of that powerful tribe by putting to death one of their envoys who had come to claim the annual tribute, and brought them into the field against him. On learning that his brother was sorely beset, Sultan Shāh left the protection of the Ghūrides and joined the Kara-Khitāys, whose queen he persuaded that the Khwārazmians were anxious for his return to the throne. As the Queen-Gūr-Khān was incensed against Tekish, she allowed herself to be gained over by Sultan Shāh, and sent her husband Karmā[338] with a large force into Khwārazm to defend the rights of Sultan Khān. Tekish, hearing of their advance, commanded the waters of the Jīhūn (Oxus) to be diverted across their line of march, so that the progress of the Kara-Khitāys was rendered almost impossible. Meanwhile he busied himself with military preparations. Karmā, seeing clearly that Sultan Shāh’s pretensions to the esteem of the Khwārazmians were unfounded, led his army home. Sultan Shāh, with his own followers and a small body of Kara-Khitāys, marched to Sarakhs, and, evicting its governor, established himself there. In A.H. 576 (1180) we find him at the head of 10,000 horsemen, and lord of Nīshāpūr. In A.H. 582 (1186) Tekish set out for Khorāsān with a large army; while Sultan Khān hastened to Khwārazm by another road. These hostilities between the two brothers continued with only short intermissions until the death of Sultan Shāh in A.H. 589 (1192), when Tekish became master of all Khorāsān and Khwārazm.[339] In A.H. 590 (1194) he entered Persian `Irāk and overthrew Toghrul III., the last of the great Seljūks of Persia.[340] After adding Ray, Isfahān, and other important towns to his dominions, he obtained an investiture from Caliph Nāsir li Dīn-illāh of all the countries which he had conquered. From this epoch-time till his death Tekish appears to have paid tribute regularly to the Gūr-Khān, and retained his friendship. He recommended his son and successor to follow the same policy, for the Kara-Khitāy were a bulwark against the dreaded hordes of the East.[341]