On August 21, 1264 , Kublai Khan accepted the surrender of his younger brother Ariq Böke at Xanadu, at the end of the Mongol civil war. An excerpt from the article:
"Gathering Power
In 1236, Kublai's uncle Ogedei Khan granted the young man a fiefdom of 10,000 households in Hebei Province, northern China. Kublai did not administer the region directly, allowing his Mongol agents a free hand. They imposed such high taxes on the Chinese peasants that many fled their land. At last, Kublai took a direct interest and halted abuses, so that the population grew once more.
When Kublai's brother Mongke became Great Khan in 1251, he named Kublai Viceroy of Northern China. Two years later, Kublai struck deep into southwest China, in what would be a three-year campaign to pacify Yunnan, the Sichuan region, and the Kingdom of Dali.
In a sign of his growing attachment to China and Chinese customs, Kublai ordered his advisors to select a site for a new capital based on feng shui. They chose a spot on the frontier between China's agricultural lands and the Mongolian steppe; Kublai's new northern capital was called Shang-tu (Upper Capital), which Europeans later interpreted as "Xanadu."
Kublai was at war in Sichuan once again in 1259, when he learned that his brother Mongke had died. Kublai did not immediately withdraw from Sichuan upon Mongke Khan's death, leaving his younger brother Arik Boke time to gather troops and convene a kuriltai, or selecting council, in Karakhoram, the Mongol capital. The kuriltai named Arik Boke as the new Great Khan, but Kublai and his brother Hulagu disputed the result and held their own kuriltai, which named Kublai the Great Khan. This dispute touched off a civil war.
Kublai, the Great Khan
Kublai's troops destroyed the Mongol capital at Karakhoram, but Arik Boke's army continued fighting. It was not until August 21, 1264, that Arik Boke finally surrendered to his older brother at Shang-tu.
As Great Khan, Kublai Khan had direct control over the Mongol homeland and Mongol possessions in China. He was also the head of the larger Mongol Empire, with a measure of authority over the leaders of the Golden Horde in Russia, the Ilkhanates in the Middle East, and the other hordes.
Although Kublai exerted power over much of Eurasia, opponents to Mongol rule still held out in nearby southern China. He needed to conquer this region once and for all and unite the land."