A century later still, and in another region, we come upon the (now) most famous of all Eastern freethinkers, Omar Khayyám. He belonged to Naishápúr in Khorassan, a province which had long been known for its rationalism, [1102] and which had been part of the nucleus of the great Asiatic kingdom created by Sultan Mahmoud of Ghazni at the beginning of the eleventh century, soon after the rise of the Fatimite dynasty in Egypt. Under that Sultan flourished Ferdusi (Firdausi), one of the chief glories of Persian verse. After Mahmoud's death, his realm and parts of the Khalifate in turn were overrun by the Seljuk Turks under Togrul Beg; under whose grandson Malik it was that Omar Khayyám, astronomer and poet, studied and sang in Khorassan. The Turk-descended Shah favoured science as strongly as any of the Abassides; and when he decided to reform the calendar, Omar was one of the eight experts he employed to do it. Thus was set up for the East the Jaláli calendar, which, as Gibbon has noted, [1103] "surpasses the Julian and approaches the accuracy of the Gregorian style." Omar was, in fact, one of the ablest mathematicians of his age. [1104] His name, Omar ibn Ibrahim al-Khayyámi, seems to point to Arab descent. "Al-Khayyámmi" means "the tent-maker"; but in no biographic account of him is there the slightest proof that he or his father ever belonged to that or any other handicraft. [1105] Always he figures as a scholar and a man of science. Since, therefore, the patronymic al-Khayyámi is fairly common now among Arabs, and also among the still nomadic tribes of Khuzistan and Luristan, the reasonable presumption is that it was in his case a patronymic also. [1106] His father being a man of some substance, he had a good schooling, and is even described in literary tradition as having become an expert Koran scholar, by the admission of the orthodox Al Gazzali, who, however, is represented in another record as looking with aversion on Omar's scientific lore. [1107] The poet may have had his lead to freethought during his travels after graduating at Naishapur, when he visited Samarkhand, Bokhara, Ispahan, and Balk. [1108] He seems to have practised astrology for a living, even as did Kepler in Europe five hundred years later; and he perhaps dabbled somewhat in medicine. [1109] A hostile orthodox account of him, written in the thirteenth century, represents him as "versed in all the wisdom of the Greeks," and as wont to insist on the necessity of studying science on Greek lines. [1110] Of his prose works, two, which were of standard authority, dealt respectively with precious stones and climatology. [1111]