Taking the ancient land system in China as an example, from the gradual disintegration of the Jing Tian system in the Spring and Autumn Period and the Warring States Period, to the gradual establishment of feudal land private ownership, and then to the intensification of land purchase and merger, farmers eventually lost their land or could not live, class contradictions intensified, and farmers revolted or rioted, leading to the change of dynasties. This process seems to be a cycle of "separation" and "combination", but in fact, this development process is influenced by many factors, including changes in political system, socio-economic development, technological progress and so on.
In addition, the development of social history is not a simple cycle of "long-term separation, long-term separation must be combined". Although there may be an obvious tendency of division or unification in some periods, this does not mean that division and unification are absolute and mutually causal. In fact, the development of social history is complex and diverse, and it cannot be simply summarized by "division" and "combination".
Therefore, the development of social history is not a simple cycle of "separation" and "combination", but is influenced and promoted by many factors. In understanding the development of social history, we need to consider these complex factors and the dynamic mechanism behind them.