Toghrul Beg had no male issue. On the approach of death he selected as his successor his nephew Alp Arslān, the son of his deceased brother Chakir. Thus, in the year A.H. 455 (1063), Alp Arslān 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 vezīr, 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 `Alī, better known as Nizām ul-Mulk, or Regulator of the State, was born in Tūs 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 Seljūks. The post of chief vezīr, 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 Arslān 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 Shāh, 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 Khān of Samarkand, who, on hearing of the death of Alptagin, had presumed to lay siege to Tirmiz, a town included in the Seljūks’ realms, though it lay on the right bank of the Oxus.[290] He soon drove the Khān back, and forced him to sue for peace. Melik Shāh 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 Bokhārā and Samarkand. Pushing beyond the last-named city, he threatened to invade the territory of the Khān of Kāshghar,[291] who, overcome by fear, consented to recognise the suzerainty of the Seljūks,[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 Müller[293] aptly compares Alp Arslān and Melik Shāh with Trajan and Hadrian. Brilliant as were the military successes of Melik Shāh, 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 Islām. There is, however, one