The beginning of the month Silhidje, in the 553rd year of the Hegira, Hulaku crossed the Oxus by a temporary bridge, and amused himself by lion hunting on the hither side. Here winter overtook him, and the cold was so severe, that most of his horses perished. He was compelled to wait till spring, when Arghun Khan appeared at his command in the camp; the political affairs of the latter were conducted by his son Gherai, Ahmed Bitegi, and Khoja Alaeddin Ata-mulk, the vizier, writer of the celebrated historical work Jehan Kusha (_Conqueror of the World_). Hulaku marched from Shirgan to Khawaf whence being himself attacked with indisposition, he despatched his general, Kayu Kanian, on the conquest of Kuhistan. He went himself to Tus, the native city of the greatest Persian poet, astronomer, and vizier, Ferdusi, Nassireddin, and Nisam-ol-mulk; the renowned burial-place of the Imam Ali Ben Mussa Risa, and established his quarters in a newly-laid out garden of Arghun Aka. From thence he went to Manssuriye, where the wives of Arghun and his lieutenant, Aseddin Taher, gave him a sumptuous banquet. He then sent the Prince Shemseddin Kurt as ambassador to Nassireddin Mohtashem, Rokneddin’s governor in Sertakht. Although an old man, Nassireddin, the first patron of the astronomer of the same name, who has immortalized his memory by his ethical work dedicated to him, nevertheless accompanied the envoy in person, to the camp of Hulaku, who loaded him with marks of distinction. Hulaku, on arriving on his march at Junushan, commanded the place, which had formerly been destroyed by the Mongols, to be rebuilt, at the public expense; he then returned to Khirkan, where he sent another embassy to Rokneddin Kharshah, the lord of Alamut, summoning him to obedience and submission. Rokneddin had just ascended the throne, still reeking with the blood of his father, and followed in his political conduct the treacherous advice of his vizier, the great astronomer, Nassireddin of Tus. The latter had presented a work to the Khalif Mostrassem: for which, instead of receiving honours and rewards, as he expected, he only gained contempt and insult. Alkami, the khalif’s vizier, jealous of Nassireddin, objected to the work, that, in the dedication, the title of “Vicegerent of God on Earth,” was wanting; and the khalif, who thought it badly written, threw it into the Tigris.[252]