How to solve the time dislocation, extension and shortening effects of relativistic effects after entering the interstellar era?

There is a concept of "geographical isolation" in biology for reference. Throughout the development of human history, the relationship between the effective control range of political power and traffic is obvious. In ancient times, it was difficult to control a vast territory by relying on animal-drawn wheels (from this point of view, the Qin Empire, which established the Qin Dynasty, was worthy of the title of the first unified country), which was one of the reasons why many ancient great empires fell apart. If the interstellar distance is far enough, even if we are all human beings, it is difficult to maintain effective administrative management, and at most we can maintain nominal rule similar to the ancient tributary system in East Asia (more decentralized than the confederacy and federal form).

In addition, due to the distance between distant time and space and the differences in different interstellar environments, human evolution will also lead to species differences. Note that even if there are different races on the same earth, the greater the difference in distance and environment, the greater the difference may be until it becomes a new species. Of course, the speed of evolution is based on "ten thousand years", and the speed of relative civilization development can be ignored.

To put it simply, in the interstellar era, if we can't break through the limitations of distant distance and light speed, if we take a generation of 30 years as an estimate, interstellar immigrants 30 light years away can't expect to effectively rule their home planet. Interstellar migration is a one-way ticket regardless of success or failure, just like transplanted cuttings, it has nothing to do with it after leaving the mother.