On the death of Sultan Mahmūd, in A.H. 421 (1030), Mas`ūd’s whole energies were absorbed in withstanding the Ghuz hordes which invaded his province of Khorāsān in ever-increasing numbers. He tried in vain to conciliate them by granting fresh pasture-lands. In A.H. 425 (1034), while he was engaged in quelling a rebellion in India, a formidable rising against the Ghaznavides took place in Khorāsān, whose inhabitants felt that they were deserted by their chief and left at the mercy of the Ghuz. At the same time the prince of Tabaristān and Jurjān, deeming the occasion favourable, reasserted their independence. In the following year Mas`ūd marched northwards, and succeeded not only in driving back the Ghuz beyond Tūs and Nīshāpūr, but in bringing to submission the rebellious prince of Tabaristān. [Illustration: CENTRAL ASIAN TYPES 1. TURKOMAN 2. KIRGHIZ 3. TAJIK 4. SARI ] Meanwhile events were taking place in the north which were to render these minor successes valueless,[275] for in A.H. 425 (1034) Hārūn, the Ghaznavide governor of Khwārazm,[276] profiting by the embarrassed position of Mas`ūd, threw off his allegiance. Although the immediate result of this step was an interval of disorder, during which Hārūn was murdered, his successor persisted in a policy of rebellion, and ceased to pay any regard to the court at Ghazna. This event in itself seemed of small importance, but it brought grave results in its train. We are told that the Seljūks, in A.H. 426 (1035), helped Mas`ūd to drive the rest of the Ghuz out of Khorāsān, but the alliance did not survive this campaign; and thus, while Mas`ūd was absent in Ghazna in the following year, we find his lieutenant in Khorāsān engaged in hostilities with the Seljūks. During the same year, A.H. 427 (1036), the Ghaznavide general suffered a severe defeat at the hands of Chakir Beg in the vicinity of Merv. From this event dates the rise of the Seljūks. In A.H. 428 (1037) Merv surrendered to Chakir, and in the following year Toghrul was declared master of Nīshāpūr. Khorāsān was now practically in the hands of the Seljūk brothers. Mas`ūd had been too busily employed with troubles in India to give due attention to the protection of his richest province. At length, in A.H. 431 (1040), he determined to make a final effort to retrieve his losses, and led an army in person against Merv, where he suffered a final and crushing defeat at the hands of Chakir and Toghrul.[277] He still clung to Khorāsān with all the energy of despair. Leaving his son in Balkh, he hastened to India to raise a fresh army. But his influence with his troops had gone, and no sooner had he crossed the Indian frontier than his lawless soldiers began to plunder the treasures which had been accumulated by his illustrious father. When they recovered their senses they “were seized with a dread of punishment, and came to the sudden resolution of reinstating Mohammad,[278] who was a prisoner in the