Defensive wall

Defensive walls were used to enclose settlements from prehistory into the modern period. Generally, these are referred to as city walls or town walls, although there were also walls, such as the Great Wall of China and the Atlantic Wall, which extended far beyond the borders of a city and were used to enclose vast regions.

Morocco and Western Sahara

• In the 1980s, Morocco built a system of sand wall defenses, the Moroccan Wall (also known as the "Western Sahara walls" or "berm"), to keep the Polisario out of the Western Sahara.