When Yan Yanliang attacked the Southern Song Dynasty, Xu Jin controlled a vast area, and its comprehensive national strength was the strongest among all East Asian countries. However, at this time, although the Southern Song Dynasty was on one side, it controlled the rich Jiangnan area, and its comprehensive national strength was not much weaker than that of Xu Jin. If war really breaks out, it's hard to say who will win and who will lose. At the same time, Jin has always been famous for its powerful cavalry. However, the Southern Song Dynasty is located in the south of the Yangtze River, with many rivers, and the terrain conditions are not conducive to the Jin State, and the Southern Song Dynasty water army is far stronger than the Jin State water army.
In addition, there were many outstanding generals in the Southern Song Dynasty at that time. Their ability to lead troops to fight was outstanding, and they were not afraid of the Xu Jin army in the north. At that time, the Southern Song Emperor Zhao Gou was also very confident. With his strong national strength and favorable terrain, he was fearless when facing Yan Hongliang. It is true that Wan Yanliang's dream of attacking the Southern Song Dynasty was shattered mainly because of civil strife, but at this time, the Southern Song Dynasty was not afraid of Xu Jin, and Xu Jin did not have absolute strength to win the war.
Finally, although Jin ruled most of the Central Plains at that time, and the sphere of influence seemed to be very large, most Han people in the Central Plains did not obey the rule of Jin, and they always wanted to restore the Han family. Therefore, if Yan Hongliang goes south to send troops, the Han people in the Central Plains will definitely rise up and overthrow the rule of Xu Jinguo. At that time, Yan Yanliang will certainly attend to one thing and lose sight of another, so even without civil strife, Yan Yanliang could not complete the great cause of eliminating the Southern Song Dynasty.