I would like to hear more on this, this is fascinating.
I've heard China described as a civilization state rather than a nation state. The people of the Chinese civilization see themselves as a part of an ordered universe defined by Confucianism. At the center is the emperor, a god-king, son of heaven who is the head of the gigantic Chinese household. This is the proper state of the civilization. A fragmented household with multiple heads is the antithesis to Confucianism and Chinese identity. It is therefore unholy, against the will of heaven.
Chinese history has multiple periods of division, but Confucian historians do not treat these as legitimate periods of history. They are seen as transitional and abhorrent, unholy times of Confucian dark age despite the fact that plenty of records were kept and that the arts and culture flourished. They represent periods when men of virtue (the Confucianists) couldn't get their act together to pull off a central government.
The Confucianists serve as the clerical class of China. When a new dynasty is founded, inevitably the conqueror must seek out the support of the Confucianist/clergical class. It's only with this support that a dynasty is viable. In times of division, rulers of various kingdoms derive their legitimacy through claims on the imperial throne, or profess loyalty to a puppet emperor. They don't formally break away to form a nation state as this would surely alienate the Confucianists and his own subjects.
Throughout Chinese history, whenever there have been periods of division there have always been attempt to unify the empire. The attempt itself is seen as virtuous. The closest analogy would be a crusade or jihad in Abrahamic religions.
When China broke up into warlord fiefdoms in the early 20th century (an unusually short period of division by Chinese standards), there was a instant crusade for unification. Chiang Kai-shek was lionized for doing this, despite his obvious short comings. His ultimate failure to consolidate China was by itself an indictment against his legitimacy. Similarly Mao was enormously popular (most certainly the Chinese leader with the most fanatical following in history) largely due to his achievement in creating the most centralized Chinese state ever. In other words, these men were seen as messiahs. One does not judge a messiah by earthly standards of morality alone.
Despite all of Mao's atrocities he is still accorded great respect that mystify Westerners. What Westerners are missing is the religious element of Chinese culture. This is easy to miss because the Chinese do not practice religion like Abrahamic cultures. They don't go to temples and chant from a holy book. This process is much more subtle. It's internalized. It's not even conscientiously articulated among the Chinese. But if you look for the manifestations of religion, it's all there. The Confucian faith runs deep in the background. Chinese history start to make a lot more sense along these lines. In modern times it can be disguised as Nationalism, a concept relatively new in Western history and thus it's easy to think of Chinese attitudes to land and history as nationalistic. However this is a uniquely Chinese brand of nationalism, an offspring of its ancient religious faith, thus there is much more than meets the eye.