The Qing emperor who seriously discussed this issue was Gan Long. Like the previous generation, Qianlong believed that Liao and Jin were a "legitimate" dynasty, not a vassal state. But as for the question of who inherits the so-called "orthodoxy" between Song, Liao and Jin, his attitude is very clear, that is, Song is orthodox, and Liao and Jin are not. He has expressed it many times. If we want to say the reason for the prosperity, it is that the ruler did not complete reunification and did not inherit the orthodoxy of the previous generation, which is not in line with the orthodoxy of his old man's house. 1768 compiled the "General Theory of Imperial Examination", and the title of the Jin Dynasty was marked from the first year of Song Qinzong Jingkang (1 126), with the Song Dynasty above and the Jin Dynasty below. 1773, titled "Cloud Map of Dajinde": Although Fu and Song moved south, orthodoxy should be returned to Song. The Yuan Dynasty and the Song Dynasty perished, and Liao and Jin were unorthodox. In 178 1 year, the treasurer refuted Yang Weizhen's statement that the Yuan Dynasty inherited the Song Dynasty instead of the Liao and Jin Dynasties, and issued an imperial decree, which showed that Yang Weizhen was right: the orthodox husband was reborn. After the Eastern Jin Dynasty, although Song, Qi, Liang and Chen were on the left side of the river, they inherited the orthodoxy of the Jin Dynasty. At that time, if Tuoba GUI's general trend was strong, the Northern Qi and Northern Zhou Dynasties followed it, which was even worse than that of the Southern Dynasties, and China's orthodoxy had to be returned to Song, Qi, Liang and Chen, which inherited it. After the Sui Dynasty, it was a great unification to mix one region with another. That is, at the end of the Tang Dynasty, the buffer region was uneasy, from Zhu Wen to Guo Wei. , or self-stealing, or being a traitor. For more than 50 years, it is easier to count surnames, and even to be a vassal and nephew in Qidan. China is in the same strain. Before the Song Dynasty, it had to rely on the orthodoxy of Liang, Tang, Jin, Han and Zhou. As for Song Nan crossing Lin 'an, Liao, Jin and Yuan started from the north one after another, and Hebei and Song were elected.