This is the rise and fall of civilizations, while expansion is possible in the sense of, the majority of people can "win" at their culture (or have a clear path to), a civilization is successful. In Rome, and America this usually means economic improvement. In Egyptian times, this meant falling in line with the religion. Carroll Quigley has a very nice framework for what is a civilization. Let's just say he was a very influential historian, mentor of one rather recent US president.