Kublai was born in 1215, the second son of Tolui and a grandson of Genghis Khan. When his brother Möngke became Great Khan, Kublai was given northern China to govern, and there he learned that steppe methods alone could not rule a land full of farmers. He kept Chinese scholars such as Liu Bingzhong at his side and rebuilt the tax and administrative system, which earned him suspicious looks from steppe princes who thought he had gone over to Chinese ways.
In 1253 he conquered the kingdom of Dali in the southwest, opening a route that flanked the Southern Song, and from 1258 he served on the Song front under Möngke. Everything changed when Möngke died suddenly on campaign in 1259. Kublai hurried north, held a kurultai at his own base of Kaiping and was proclaimed Great Khan; a month later his brother Ariq Böke was proclaimed Great Khan in the capital, Karakorum.
The war between the brothers lasted four years. When open battle settled nothing, Kublai took hold of every supply route feeding Karakorum. A capital in the middle of the grassland had to be fed with grain from the south, and after a hungry winter Ariq Böke surrendered in 1264. The victory did not restore the authority of the Great Khan, however. The western khanates were already going their own way, and in Central Asia Kaidu opposed him for more than thirty years.
Kublai built a new capital, Dadu, where Beijing stands today, and in 1271 renamed the state Great Yuan after a phrase from a Chinese classic. In 1279 the last Song resistance collapsed at Yamen, and all of China was his. He spread paper money, organized the relay stations, and had the Tibetan monk Phags-pa design a new script for writing Mongolian. Marco Polo visited Dadu in these years, and the account he left shaped how Europeans imagined the East.
His later campaigns went badly. The fleets sent against Japan in 1274 and 1281 were wrecked by great storms, which the Japanese called the divine wind, or kamikaze. Expeditions to Vietnam and Java brought no lasting result. After losing his favourite wife Chabi and then his chosen heir Zhenjin, he weakened noticeably, and he died at Dadu in 1294. His choice to be a Great Khan and a Chinese emperor at once became the frame of the Yuan state, but it could not reverse the empire's drift into four separate realms.