Border zones are areas near borders of states that have special restrictions to movement. Governments may forbid unauthorized entry to border zones and restrict property ownership in the area. The zones function as buffer zones specifically monitored by border patrols in order to prevent illegal entry. Restricting entry aids in pinpointing illegal intruders. Between hostile states, the border zone can be heavily militarized with mine fields, barbed wire and watchtowers.
The Iron Curtain was a collective term for the border between the Western states and the Eastern Bloc. The restrictions on building and habitation made the area a "green corridor".