Kaidu perfected the and the "infinite chase." He would raid deep into Yuan territory (Mongolia and Xinjiang), burn pastures, steal horses, and vanish into the desert before a counter-force could arrive. When the Yuan army pursued, he would lead them into waterless steppes, then circle around to attack their supply lines. His mobility was terrifying: his warriors could ride 100 miles a day on remounts, fighting in the morning and retreating by nightfall.
The battle lasted for three days. On the first day, Kaidu’s horse archers annihilated the Yuan vanguard. On the second, Duwa’s Chagatai heavy cavalry broke the Yuan center. But on the third day, Qaishan used a feigned retreat of his own, drawing Kaidu’s warriors into a crossfire of crossbowmen and mangonels (stone throwers). Kaidu was shot in the arm and shoulder. His army disintegrated. Kaidu was carried from the field in a felt wagon. He died of his wounds later that year, near the Talas River (modern Kyrgyzstan). On his deathbed, he whispered to Duwa: “Do not yield. The city-dwellers will rot from within. Fight on for the felt tent.” Kaidu perfected the and the "infinite chase
Möngke conducted a brutal purge of the Ögedeid and Chagatai families, whom he saw as rivals. Kaidu’s father, Kashin, had already died, but Kaidu himself was spared due to his youth and obscurity. However, he was placed under close surveillance. According to The Secret History of the Mongols , the young prince was assigned a small, impoverished appanage in the remote Emil River valley (modern-day eastern Kazakhstan). It was a deliberate insult—a barren, rocky region incapable of supporting a large army. But it was here that Kaidu forged his character. He learned patience, honed his skills in riding and archery, and began quietly building a network of loyal followers among the discontented clans. The memory of the Toluid usurpation and the humiliation of his family never left him. The death of Möngke Khan in 1259 triggered the great Toluid Civil War between his brothers: Kublai (who favored Chinese-style sedentary rule) and Ariq Böke (who championed Mongol traditionalism). Kaidu shrewdly supported Ariq Böke, seeing a chance to restore Ögedeid power. Although Ariq Böke lost in 1264, Kaidu emerged not as a defeated vassal, but as a defiant warlord. He refused to appear at Kublai’s new capital, Khanbaliq (modern Beijing), to swear fealty. The battle lasted for three days