camp.”[279] Mas`ūd was captured, and in the following year, A.H. 433 (1042), murdered by his own nephew. The princes of Ghazna continued to reign until A.H. 555 (1160),--in fact, they outlasted the Seljūks of Central Asia,--but no chief of the dynasty ever attained to the greatness of its earlier representatives. Their hostilities with the Seljūks were finally brought to a close by a treaty concluded in A.H. 451 (1059) between Chakir and Ibrāhīm, the then ruler of Ghazna, who thereby for ever lost the province of Khorāsān.[280] CHAPTER XVIII THE SELJŪKS Toghrul Beg’s career of conquest is admirably epitomised by Gibbon in the 57th chapter of his immortal work. After driving the Ghaznavides back to India, he overthrew the powerful dynasty of the Būyides,[281] and with their fall the whole of Persia passed into the hands of the Turks. “By the conquest of Āzerbāyjān, or Atropatene, he approached the Roman confines, and the shepherd presumed to despatch an ambassador or herald to demand the tribute and obedience of the Emperor of Constantinople.”[282] The expeditions of these fortunate brothers, Toghrul and Chakir, in their results at all events, more closely resembled the migration of entire peoples than military campaigns. By the year A.H. 440 (1048) Āzerbāyjān, Mesopotamia, and Asia Minor were entirely overrun by Turkish bands. Four hundred years before this a huge wave of conquering Arabs and Persians had swept in an easterly direction over all Persia as far as the Oxus and beyond it. We now find a still vaster influx of Turks over the same country, but starting where the other had ended. The first flood-tide took the form of a religious war into the infidel countries, and brought with it the influence of culture and solid learning. The reflex wave was an irresistible migration of savage tribes, who, though well-nigh destitute of any tincture of letters,[283] were still, it must be remembered, the children of Islām. The marks left on the East by the Western wave were ethnographically slight, but psychically of great importance; while precisely the opposite is true of the second immigration. Bokhārā and Balkh became, and for centuries remained, the centres of Mohammedan lore, while Asia Minor and Āzerbāyjān were the permanent abodes of the descendants of the Seljūks. The forces of the two brothers were probably augmented by the westward flow of new bands of Turks, and victory attended them wherever they turned. In A.H. 449 (1055) Toghrul Beg entered Baghdād, and helped to establish the Caliph Kā´im on his throne.[284]