Kaidu’s war was not merely dynastic; it was ideological. He saw Kublai’s adoption of Chinese court rituals, paper money, fixed taxes, and a bureaucratic state as a betrayal of Genghis Khan’s Yassa (law). In Kaidu’s eyes, a Mongol should live in a felt tent ( ger ), follow the herds, and owe allegiance only to a khan who proved himself on horseback. He famously declared: “Kublai has polluted himself with the customs of the peasants. Our grandfather’s empire was won with the bow and the horse, not with brushes and ink.”
In 1303, two years after Kaidu’s death, his former allies signed a peace treaty with the Yuan. The Mongol Empire was formally recognized as four separate khanates—the Yuan, the Chagatai, the Golden Horde, and the Ilkhanate—each going its own way. The war for a single, nomadic empire was over. Kaidu, the prince of nothing but the open sky, had lost—but his hoofbeats echoed in the steppe wind for centuries. Kaidu’s war was not merely dynastic; it was ideological