What is the effect when a state acquired the territory of another state?

It is a general principle of the public law that on acquisition of territory the previous political relations of the ceded region are totally abrogated. "As a matter of course, all laws, ordinances and regulations in conflict with the political character, institutions and Constitution of the new government are at once displaced (Chicago, Rock Island and Pacific Railway Co. vs. McGlinn [1885], 114 U.S., 542).