Throughout the ancient history of China, compared with other dynasties at the end of the Han Dynasty (the comparison of historical dynasties was relative and horizontal on the whole (the external aggression and internal rebellion of the society were not absolute at that time), the objective strength was not much better, which was manifested in the low control of the central government over the localities, which led to serious civil strife. However, this is only an internal manifestation. Note that it is internal.
Looking at Dahan for more than 400 years, since Emperor Wu of the Han Dynasty, it has always maintained a strong position towards the surrounding foreigners. Generally speaking, it can not be ignored that the Han Dynasty expelled the Northern Emperor and Xirong, which was almost extinct. No matter how powerful the central government was in the Han Dynasty, local governors could send troops to suppress or expand, which was a strength. The central plains sent troops, and wherever they went, they either surrendered or fled far away. In such a powerful situation, foreigners always kept a low profile to the Han Dynasty and had no intention of aggression. Occasionally harassed, beaten, and rolled back to the grassland.
Internally, we must first clarify a concept: the reason why Han people are "Han" is because of the Han Dynasty. The Han dynasty ruled for 400 years, first came Huang Lao, then Confucius, and the Han people fought bloody battles to defend our mantle. The world (at that time) was first-class and powerful. The gentry people's centripetal degree to the Han Dynasty and the Liu royal family is far from what we can imagine now (it should be noted that the gentry represents the people in the patriarchal society-the so-called feudal society-era). Before Yuan called 18 people to seal the official position, no one dared to disrespect the big fellow. However, after that, the trend of disintegration is inevitable. Even so, no foreigner dares to enter China to make trouble.
The demise of the Han Dynasty was not caused by foreign aggression, but by civil strife.
However, since the Han dynasty, the nomadic people in the north have become increasingly powerful, and they have tasted the sweetness on the road of invading the south, and the idea of going south has become increasingly strong. However, the Han Dynasty in the Central Plains could not stop the nomadic people from going south, which eventually indirectly or directly led to the replacement of dynasties.
Therefore, Wang Fuzhi's statement is based on the comparison with later generations, combining internal and external causes.
I hope the questioner can understand the question subjectively and comprehensively.
Attachment: Article 9 of Wang Fuzhi's On Reading as a Mirror, Volume 8, Hou Han Ji Heng:
"At the end of the Han Dynasty, I will die and stand, and the enemy will come to the world. Zhang Huan, Huang and Duan Qirui all rose up, claiming to be tiger ministers. Hokuriku and Xiqiang beheaded millions of people, searched all the poor mountains and evil valleys, and wiped out several species. Xinjiang is still far away. So people are used to war and have angry ambitions. For decades, how many stones moved first when they crossed the Central Plains!
Huan, a spiritual world, is a scholar-bureaucrat who wants to do something, but can't. You must not be arrogant; The court's law and discipline must be improper; The greed of counties must not be asked. Scholar-officials want to make a difference, but only support soldiers to make efforts at the border; Secondly, drive away the thieves in the Central Plains; Fame is to be shaken up, merit is to be hidden, and human feelings are to be returned. Dark sovereignty castrates the capital and ambition to live and work in peace and contentment. Therefore, although it is either taboo or arrogant, it cannot be trapped in reopening. So everyone knows that only this is the road to fame and fortune, and few people are hurt. Scholar-officials are all happy, and all the people are also fighting for it. Therefore, since the day of the thief, the soldiers were in a state of chaos, and they also split up and became the trend of Yuan, Cao, Sun and Liu. Therefore, the country will always be weak, while the Han Dynasty was strong.
At the end of the Han dynasty, the husband was strong and the Lu was weak. If you drive them away, you will kill them, but there will be few creatures. You don't have to solve the urgency of the frontier, save the people from danger, help the country not to lean, but love is cool. People are willing to kill people, and there is no Lu to kill, but to kill themselves. If you kill yourself, you will be embarrassed; Contradictory, only ugly, but also take advantage; So, after a hundred years of mourning, the soldiers of the Three Kingdoms stopped, and the disaster of the Five Lakes began. A good soldier is ominous, so since ancient times, Li Zhuo has been rich and strong, but it has weakened in the middle and summer, while Japan is afraid of dogs and sheep. At the end of the Han dynasty, those who were greedy and quick were deeply saddened by the world. "