A group that exhibits solidarity in the face of other groups. Once the nation-state is created, it"s borders are locked in. When they began to feel threatened, the movement of citizens became much more restricted. This was first introduced by the treaty of westphalia (which ended the thirty years war: this treaty settle the question of who determines the religion in a given territory. The creation of the nation-state was a way to create a relationship between the nation and the state. This treaty is important in the modern world because it introduced the idea of sovereignty (a principle that gives the state control over a given territory and freedom from external influences over that territory) States were beginning to claim specific territories even if they didn"t have a relationship with the nation but rather a relationship with the individual rulers. Economic nationalism for the purpose of building a wealth and powerful state.