The answer is social segregation. The segregation can also be triggered by social factors that become apparent as they occur, but are not essentially government sanctioned. This could be things like casual ghettos or merely rich neighborhoods. In relations of land capital, over time in a given area, the humans will resolve down and buy or take the land. The privileged people will obtain better land which is more arable, proximate to potential capital and more beautiful views. The claim for these better habitations efforts up prices and areas considered better based exclusively on topography come to be essentially exclusionary in their population makeup.