Nation states have their own characteristics, differing from those of the pre-national states. For a start, they have a different attitude to their territory when compared with dynastic monarchies: it is semisacred and nontransferable. No nation would swap territory with other states simply, for example, because the king's daughter married. They have a different type of border, in principle defined only by the area of settlement of the national group, although many nation states also sought natural borders (rivers, mountain ranges). They are constantly changing in population size and power because of the limited restrictions of their borders.