The army of Hoolagoo was reinforced by a thousand families of Chinese firemen to manage the battering machines and fling the flaming naphtha, known in Europe under the name of Greek fire. He set forward in the month Ramazan of the 651st year of the Hejra (A.D. 1253). His march was so slow that he did not cross the Oxus till two years afterwards. On the farther bank of this river he took the diversion of lion-hunting, but the cold came on so intense that the greater part of his horses perished, and he was obliged to wait for the ensuing spring before he could advance. All the princes of the menaced countries sent embassies to the Mongol camp announcing their submission and obedience. The head-quarters of Hoolagoo were now in Khorassan, whence he sent envoys to Rukn-ed-deen, the Ismaïlite chief, requiring his submission. By the advice of the astronomer Nasir-ed-deen, who was his counsellor and minister, Rukn-ed-deen sent to Baissoor Noobeen, one of Hoolagoo's generals, who had advanced to Hamadan, declaring his obedience and his wish to live in peace with every one. The Mongol general recommended that, as Hoolagoo himself was approaching, Rukn-ed-deen should wait on him in person. After some delay, the latter agreed to send his brother Shahinshah, who accompanied the son of Baissoor to the quarters of the Mongol prince. Meantime Baissoor, by the orders of Hoolagoo, entered the Ismaïlite territory and drew near to Alamoot. The troops of the Assassins occupied a steep hill near that place. The Mongols attacked them, but were repelled each time they attempted the ascent. Being forced to give over the attack, they contented themselves with burning the houses and ravaging the country round.