[668] Ruk neddin was the eldest son of Alá-eddin; as heir presumptive he was much honored by the Ismâilahs, who made no difference between his orders and those of his father. The latter, irritated on that account, declared a younger son his successor, in spite of the people’s attachment to the eldest. Rukn-eddin, perpetually threatened by Ala-eddin’s resentment, took refuge in a well defended castle. He was suspected, and even accused by his own mother, of having been privy to the murder of his father, although he punished the murderer. [669] Holagú was the grandson of _Jengish khan_. Born in 1127 A. D., Jengish khan, in the first moiety of the thirteenth century, came with six hundred thousand Tartars from the high lands between China, Siberia, and the Caspian sea, to act his formidable part in the Southern countries, already deluged with blood by the unceasing wars of the Arabs, Persians, and Turks. The dominion of the Seljuk dynasty, torn asunder by the dissensions of their members, during forty years after Sinjar, their Sultan, last mentioned in the Dabistán (p. 440), terminated with Toghrul the Third, in 1193 A. D.; there remained still a vigorous branch of it in Jelál-eddin, sultan of Khorazm, who retired before the great conqueror towards India; he was overthrown in a great battle on the Indus, in 1222 A. D. Jengishkhan died in 1227, after having made a division of his immense empire: he gave the kingdoms of Khorassan and Kabul to his fourth son, Tuli khan, who died soon after his father, leaving four sons, the two eldest of whom were the above mentioned Maikú kán (Mangu khán), and Holagú khán. The former ruled in Tartary, the second proceeded to the conquest of Persia and the empire of the khalifs. It was necessary first to subdue the Ismâilahs.