First of all, it is debatable whether the Northern Song Dynasty is a unified dynasty, because the territory of the Northern Song Dynasty is basically the same as the territory ruled by the traditional Han regime, and the Northern Song Dynasty has indeed successfully ended the internal division of China in the Five Dynasties and Ten Countries, which is different from the Southern Song Dynasty, where the north and the south confronted each other.

As a unified dynasty, Jin was in a short period in the Western Jin Dynasty. It did contribute to ending the separation of the three countries. However, throughout history, the Jin Dynasty was the most humiliating dynasty in China's history, and was beaten out of the water by the nomadic people in the north. Its economic achievements are really different from those of the later Song Dynasty. Politically, the rulers were famous for civil strife. Culturally, metaphysics prevailed in the Jin Dynasty, and the gentry tried to escape from reality.

For the first time, the Jin Dynasty made the Chinese nation face the threat of almost national subjugation and extinction, and the population of Han people dropped sharply, which was an unprecedented dark age in the history of China.

Because of this, although Wei, Jin, Southern and Northern Dynasties and Jin Dynasties existed for so long, they were always at home and abroad. The whole China was in a period of high turbulence, and China fell into a new division in the late Jin Dynasty, which made the Jin Dynasty lose its influence and naturally lost its sense of existence.

Song dynasty was different. The Northern Song Dynasty and the Liao Dynasty maintained peace for nearly a hundred years, and the Southern Song Dynasty also struggled for many years. Generally speaking, the inland of Song Dynasty maintained a high degree of prosperity.

Economically, it reached an unprecedented peak in the feudal history of China; Culturally, the Song Dynasty, which valued literature over martial arts, really created a brilliant Song Wenhua; Scientifically speaking, three of China's four great inventions reached their acme in the Song Dynasty. Militarily, Song, like Jin, was bullied by the north to a certain extent, but it was different because Song was not bullied all the time. When the Northern Song Dynasty fought against Liao, no one was completely sure of destroying each other. (Later, because there was no brain in the Northern Song Dynasty, he helped Jin destroy Liao and set himself on fire. ) In the Southern Song Dynasty, the Jin people's southern expedition was unsuccessful. The weak Southern Song Dynasty just lasted for more than 40 years, becoming the longest supporting period among the conquered regimes in Mongolia.

Looking at this map, I feel that the Southern Song Dynasty was under great pressure. . .