At the beginning of the 13th century, China had seven separatist regimes or regions: Mongolia, Western Liao, Western Xia, Jin, Southern Song, Dali, and Tubo. Among these seven units, five were ruled by the same regime. Among them, Song and Jin were the most unified; Tubo and Mongolia were also divided. However, the historical task of unifying these seven units was completed by Mongolia. It was on the East Asian continent that a powerful steppe nation emerged in Mongolia, led by Temujin. Since the unification in 1206, the various Mongolian tribes have given full play to the military advantages of their cavalry, fought everywhere, and eliminated various political forces existing on the East Asian continent. In 1209 AD, Mongolia attacked Xixia and forced Xixia to make peace. They also attacked Xiliao, a country that was afraid of Uighurs, and gained the Urumqi, Turpan, and Hami areas of today's Xinjiang. In 211, another subordinate country of Xiliao, Ta, was occupied, and its territory expanded to the east of today's Balkhash Lake. In the autumn of the same year, the Mongols attacked Xu Jin and soon invaded Juyongguan, threatening the capital of Jin and capturing a large number of counties in Shanxi, Hebei, Shandong and Henan. In 214, the Mongols arrived in Zhongdu, and Jin Xuanzong made peace. In 1218, the Mongols occupied all of Western Liao. The Mongolian army successively captured Hedong, Hebei, and Shandong. In 211, the land north of the Golden Yellow River basically fell into Mongolian hands. In 1226, Genghis Khan personally led an army to attack Xixia and captured Gansu, Su and other states. He destroyed Xixia in June of the following year and died of illness in Qingshui in July. After his son Ogedai Khan succeeded to the throne, he continued to attack the Jin Dynasty and made an agreement with the Southern Song Dynasty to attack from the north and the south. In 1234, Meng and Cai captured Caizhou, and Jin Aizong committed suicide. At the end of the year, the emperor died in the rebellion, and Jin died. In 152, Kublai Khan conquered Dali. The following year, Dali City was captured, Duan Zhixing, the leader of the Dali Kingdom, was captured, and the Dali Kingdom was destroyed. In Mongolia in 1244, Saskatchewan Pandita, the uncle of the Tibetan religious leader Basba, met the Mongol general Kuaduan and accepted the jurisdiction of the Mongol Khan. But some Tibetan nobles were unwilling to obey the Mongols. So after Dali was destroyed, the Mongols entered Tubo, suppressed the disobedient nobles, and completely controlled Tubo. In 276, after many wars, Kublai Khan of the Yuan Dynasty occupied Xiangyang and then most of Sichuan. The middle and upper reaches of the Yangtze River were controlled by the Mongols, while the lower reaches of the Yangtze River were defenseless. Kublai Khan marched east of the Yangtze River and attacked the Southern Song Dynasty across the board. The Southern Song Dynasty surrendered in Lin'an, but Wen Tianxiang, Zhang Shijie and others continued to resist in Fujian, Guangdong and other places until the defeat of Yashan in 1279, and the Southern Song Dynasty finally perished. If the territory was divided from the empire established by the Mongols, its territory was very vast. Starting from Genghis Khan, they have reached Central Asia, West Asia and even Europe, but the Mongolian empire is not completely equivalent to the Yuan Dynasty. Why? First, when Genghis Khan was on the throne, a feudal system was implemented, and the areas west of the Tianshan Mountains, the Altai Mountains, and the Irtysh River were divided among his three sons. Although the successor to the Mongolian grassland was the Great Khan, he was only a nominal leader and had no right to interfere in the internal affairs of the feudal states. When Ogedai was in power, each feudal state could still show respect to the Great Khan. By the time of Meng Ge and Kublai Khan, there were very few connections between places. Kublai Khan, they could only manage the East Asian continent. Secondly, the political system of the Yuan Dynasty headed by Kublai Khan was very different from the rest of the Mongol Empire. Kublai Khan began to use some methods of the original Central Plains dynasty to rule. Although the scope of application was extremely limited, it had been assimilated by the Central Plains culture. Therefore, his rule could represent China in a cultural sense, while the rest of the Mongol Empire remained nomadic and could not be culturally Chinese. So the territory of the Yuan Dynasty is as follows: in the north, starting from the Irtysh River in the west and reaching the Sea of ??Okhotsk in the east; in the east, it has the northeastern part of the Korean Peninsula; southwest China includes present-day Kashmir, Bhutan, Sikkim, and northeastern Myanmar Compared with the territory of the Han and Tang Dynasties at their peak, the Yuan Dynasty not only greatly exceeded them in area, but also far exceeded them in the degree of control. In addition to the Tubo area, the Yuan Dynasty established running script provinces throughout the country, including the Yinshan Mountains and the area north of the Liao River, which had never been formally established during the Han and Tang Dynasties.