According to China's historical theory, the consolidation of autocratic monarchy is always the primary condition and symbol of national unity, so great unity can be used in the sense of ruling the whole country or national unity. The reason is that the concept of great unification is actually around the establishment of universal kingship. Therefore, the most important mission of all dynasties is to "turn the world into one family." Even if there is a separatist regime, it is generally considered temporary and abnormal. The so-called "the general trend of the world will be combined for a long time." On the other hand, under the infiltration of Confucian culture, minority rulers take the world as their responsibility and pursuit. For example, Fu Jian, the former emperor of Qin Dynasty, who was born in the imperial clan, called his ministers to discuss the southern expedition and said, "I have worked hard for twenty years, and I have made four plans, but the southeast corner has not been turned into a king. Every time I think that the world is different, I have to stop eating. " Although the cause of conquering gold and reunifying the whole country failed due to timing and other reasons, Fu Jian's desire for reunification with the world was not pretentious, which reflected his understanding of the inevitability and rationality of China's historical development and his strong sense of historical mission. During the confrontation between Song and Jin Dynasties, King Jin Hailing also suggested that the unification of the whole world is the orthodoxy, and there is no need for the unification of the Song Dynasty, so the Jurchen rulers are also qualified. He also wrote a poem: "Wan Li is mixed with cars and books. Is there any other border defense in Jiangnan?" Kublai Khan changed his title to "Dayuan" in the eighth year of Zhiyuan (127 1), issued an imperial edict, declared himself to be the feudal orthodoxy of China, and defined the war of conquering and unifying the whole country in Song Dynasty as a just cause of "uniting the discipline with fewer kings".