In 960, Zhao Kuangyin added a yellow robe to replace Hou Zhou, set the capital kaifeng, and established the Great Song Dynasty. It is another unified dynasty established by the Han people after the Tang Dynasty.
However, the land area of the Song Dynasty shrank considerably. The sixteen prefectures of Yanyun were ceded, Yunnan was established independently, and Li Yuanhao established western Xia in Yinchuan, Ningxia, and the land that was originally the territory of the Tang Dynasty was lost. According to the data, the Song Dynasty was the smallest dynasty in Chinese history.
Second, the military strength of the Song Dynasty was very weak. In order to prevent the military generals from becoming dominant, Zhao Kuangyin has always adopted the political strategy of civilian officials to suppress military generals, and has become the national policy of the Song Dynasty, which is why the Song Dynasty's foreign wars have always been a major reason for losing more than winning. Second, the Song Dynasty did not have a vast steppe to train cavalry troops, the quality of horses was extremely poor, and in the face of the fierce Mongols, the Jurchen cavalry could only collapse.
Again, the lack of Yanyun Sixteen Prefectures left the Song Dynasty with no danger to defend. Yanyun Sixteen Prefectures is today's Shanxi, Beijing, Tianjin, Hebei area, there are Taihang Mountain, Yanshan and many other natural barriers, but all in the hands of the enemy, resulting in Jurchen cavalry can drive straight in, all the way to the city of Bieliang.
It can be seen that the military strength of the Song Dynasty was weak, the land area was greatly reduced, and even if the literature and economy of the Song Dynasty were a peak of the feudal era, it could not become a great dynasty compared with the Han and Tang Dynasties.