In the year 1257, or 1258, his uncle named Naiam, being then thirty years of age, who had the command of so many countries and nations, that he could easily have mustered 400,000 horse, became puffed up with youthful vanity, determined to take away the empire from his lord, and drew into his schemes another great Tartar prince, named Caydu, who was nephew to Kublai, and commanded on the borders of great Turkey, and who engaged to bring an 100,000 men into the field, in aid of the ambitious project of Naiam. Both of these confederates began to gather forces; but this could not be done so secretly as not to come to the knowledge of the great khan, who immediately set guards on all the roads into the desert, and assembled all the forces which lay within ten days journey of Cumbalu, the imperial residence. In twenty days, he had collected an army, amounting to 360,000 horse and 100,000 foot, a large part of which vast force was composed of huntsmen and falconers, and persons belonging to the imperial household. With this army, Kublai marched with all expedition into the province occupied by Naiam, where he arrived at the end of twenty-five days march altogether unexpectedly, and before Naiam had completed his preparations, or had been joined by his confederate Caydu. After giving his troops two days rest, and having encouraged his men in the confident expectation of victory, by means of his astrologers and soothsayers, he advanced towards the encampment of Naiam, and appeared with his whole army on a hill, over against the camp of the rebels, who had not even sent out any scouts to procure intelligence.
Kublai-khan was seated on the top of a wooden castle, carried by four elephants, and filled with archers and cross-bow men, from which the royal standard was displayed, on which the pictures of the sun and moon were pourtrayed. Dividing his army into three bodies, he kept one as a reserve on the hill beside himself, and sent the two wings to attack the army of Naiam, who resolved to stand the issue of a battle. To every ten thousand horse in the army of Kublai, five hundred light armed footmen with lances were assigned, who had been taught to leap up behind the horsemen on any occasion when flight or retreat became necessary, and were instructed to alight, and kill the horses of the enemy during battle. The two armies joined in a well contested battle, which lasted from morning till mid-day, when Naiam was made prisoner, and all his followers submitted themselves to the clemency of the victor; and having renewed their oaths of allegiance, were pardoned and dismissed, having a new governor set over them, in whose fidelity the great khan could confide.