"Tang, Song, Yuan, Ming and Qing Dynasties" in the list of dynasties, why are Liao and Jin not among them?

Liao and Jin Dynasties are not listed in the list of "Tang, Song, Yuan, Ming and Qing Dynasties" because they are only a transition of history and have little influence on later generations. In the order table of dynasties, only those countries with great influence or dynasties with representative significance in the process of historical development can stay in it. Some small countries or dynasties that did not last long will be directly ignored.

For example, in our Song Dynasty, he was different and had a great influence on the times. During the Song Dynasty, both economic development and political strategy were promoted rapidly, and it was an indispensable dynasty in the history of China. Its position in history is far from that of Liao and Jin Dynasties. Therefore, many historians did not include Liao and Jin in the list of dynasties.

The Song Dynasty followed the Liao State, but it was somewhat unreasonable, because our Northern Song Dynasty was established in the late Liao Dynasty. Comparing the Liao Dynasty and the Song Dynasty, we once unified China in the Northern Song Dynasty and occupied a lot of land. Judging from the traditional concept of Chinese historiography, the Song Dynasty tampered with the history of the previous dynasty, so it can stay in the list of dynasties.

Another most important reason is the historical materials they left behind. There are few related documents left by us in Liao and Jin Dynasties, and some institutional rites and music of the imperial court are very old. But the Northern Song Dynasty was different. They not only opened up territory for the country, but also wrote many history books. It is convenient for future generations to refer to and learn. Only with a large number of historical materials can we recognize the historical significance of this dynasty.