Kaidu, a nephew of the Great Khan, rules here. He and his uncle have had their run-ins. Polo describes how the armies fight:

When they go to war, each is obliged to carry with him sixty arrows, thirty of which are of a smaller size intended for shooting at a distance, but the other thirty are larger, and have a broad blade. These they use at close quarters and strike their enemies in the faces and arms and cut the strings of their bows and do great damage with them. And when they have shot all their arrows they take their swords and maces and give one another heavy blows with them(4424-27).

Kaidu proves to be a successful warrior and makes war on another of the Great Khan's sons, Nomogan, at Karakorum. The battle is savage and features a great many men: “their numbers were about equal—neither exceeding sixty thousand horsemen well armed with bows and arrows, and each with a sword, mace, and shield” (4444-45). Polo includes a description of a nacar, a sort of drum, that Mongols must hear before they are allowed to begin a battle. The two sides grind each other down, but neither army gives ground.