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 Buyides,281 and with their fall the whole of Persia passed into the hands of the Turks. “By the conquest of Azerbayjan, 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) Azerbayjan, 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 Islam. 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. Bokhara and Balkh became, and for centuries remained, the centres of Mohammedan lore, while Asia Minor and Azerbayjan were the permanent abodes of the descendants of the Seljuks. 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 Baghdad, and helped to establish the Caliph Ka´im on his throne.284

Toghrul Beg had no male issue. On the approach of death he selected as his successor his nephew Alp Arslan, the son of his deceased brother Chakir. Thus, in the year A.H. 455 (1063), Alp Arslan became lord of a kingdom which extended from the Oxus to the Euphrates, and from the Caspian to the Persian Gulf. One of his first measures was to rid himself of his uncle’s vezir, and appoint in his stead a man who afterwards bore one of the most exalted names in the history and literature of the East. Hasan ibn `Ali, better known as Nizam ul-Mulk, or Regulator of the State, was born in Tus in A.H. 408 (1018), and early displayed signs of administrative power. He held office first under the Ghaznavides, and later, at Balkh, under the Seljuks. The post of chief vezir, which now fell to his lot, he continued to hold for a period of thirty years. He was celebrated alike for justice, tolerance, and literary attainments.285

It was under Alp Arslan that the Turks first invaded the Roman Empire.286 Having temporarily satisfied his ambition in the West,287 he returned to his capital, and formed the project of crossing the Oxus and invading the countries whence his ancestors had come. His career was, however, cut short in A.H. 465 (1063) by a mortal wound received at the hands of a man whom he had condemned to death.288 He was succeeded by his son Melik Shah, whose claims were disputed by several rivals,289 but these were disposed of with little difficulty. In A.H. 446 (1073) he engaged in warfare with Altagin, the Turkish Khan of Samarkand, who, on hearing of the death of Alptagin, had presumed to lay siege to Tirmiz, a town included in the Seljuks’ realms, though it lay on the right bank of the Oxus.290 He soon drove the Khan back, and forced him to sue for peace. Melik Shah apparently remained on peaceful terms with the Turks until A.H. 482 (1089), when, in response to a call from the oppressed inhabitants of Transoxiana, he crossed the great river and made himself master of Bokhara and Samarkand. Pushing beyond the last-named city, he threatened to invade the territory of the Khan of Kashghar,291 who, overcome by fear, consented to recognise the suzerainty of the Seljuks,292 both in his coins and in the public prayers. At the zenith of his fortunes the great Sultan held sway from the frontiers of China up to the gates of Constantinople. August MÜller293 aptly compares Alp Arslan and Melik Shah with Trajan and Hadrian. Brilliant as were the military successes of Melik Shah, they are cast into the shade by his cultivation of the peaceful arts and his sedulous care for the development of his territories. Though five years passed by ere he was firmly established on his throne, the remaining fifteen years of his reign were attended by a degree of internal prosperity, an advance in literature and learning, which will ever associate his name with one of the most brilliant epochs in the history of Islam. There is, however, one great blot on his escutcheon: his treatment of his able and faithful minister, Nizam ul-Mulk. Influenced by lying reports brought to his ears by the enemies of the vezir, he degraded his devoted servant and indirectly brought about his death. For, shortly after Nizam ul-Mulk’s removal from office, he was murdered by an assassin,294 employed perhaps by his successor in office, who feared a change in the Sultan’s sentiments, A.H. 485 (1092). Melik Shah did not long survive the fallen minister. Within a month he was seized with a violent illness, which terminated his life in the thirty-eighth year of his age.

He left four sons, who each in turn succeeded to his throne.295 The youngest, Mahmud, was only four years of age when his father died; but the ambition of his mother, the Sultana Khatun Turkan, placed the crown upon his infant head, and the Caliph Muktadi was prevailed on to have his name mentioned in the public prayers. The Sultana marched to Isfahan, preceded by the corpse of Melik Shah. Berkiyaruk, the eldest prince,296 was residing there; but, powerless to resist, he retired to Ray, attended by Mu`ayyad ud-Dawla, the son of the late vezir Nizam ul-Mulk, who warmly espoused his cause, with all the adherents of his family. This support enabled him to return, and Khatun Turkan was compelled to resign a great part of her treasures as the price of permission to retain control of Isfahan. All her schemes of aggrandisement were soon afterwards terminated by her own death and that of her son, A.H. 487 (1104).

The death of the Caliph Muktadi, which occurred about the same period, induced Berkiyaruk to go to Baghdad, where he confirmed Mostadhhir as the new Caliph, and was in return hailed by him as Sultan of the empire. He enjoyed that dignity for eleven years,297 but his reign was a perpetual war in which his nearest relatives and all the great nobles of the state were engaged. His usual residence was Baghdad. His brother Mohammad ruled over Azerbayjan, while Sanjar established a kingdom in Khorasan and Transoxiana, whence he extended his conquests over the fallen princes of Ghazna, compelling them to pay him tribute. Berkiyaruk, who appears to have had an excellent disposition, and to have been wanting neither in courage nor conduct, died on a journey from Isfahan to Baghdad,298 A.H. 498 (1104). He felt his end approaching, and before he expired made his army take the oath of fidelity to his son Melik Shah II. The young prince was, however, unable to resist his uncle Mohammad, who seized Baghdad treacherously and took him prisoner, A.H. 498 (1104). The reign of Mohammad, which lasted thirteen years, was remarkable only for continual civil disturbances, and for the wars which his generals carried on in Syria against the European armies engaged in their crusade to recover the sacred city of Jerusalem and the Holy Land from the Mohammedans. He died at Isfahan in A.H. 511 (1117), and was nominally succeeded by his son Mahmud, who was almost immediately reduced by his uncle Sanjar to the condition of a dependant.299 Sanjar, who had been governor of Khorasan and its dependencies for the past twenty years, now became Sultan, and as such enjoyed a reign of no less than forty years, A.H. 511–552 (1117–1157).

We must now turn our attention to Transoxiana and the East, where important events were passing.