The Free Zone or Liberated Territories is a term used by the Polisario Front to describe the part of Western Sahara that lies to the east of the Moroccan Berm (the Moroccan border wall) and west and north of the borders with Algeria and Mauritania, respectively. For Morocco, it is a buffer territory.
The area is separated from the rest of the Western Sahara territory by "a 2,200 kilometer [1,367 mi]-long wall...flanked by one of the world's largest minefields. The border is often referred to as the "Berm".
The zone was established as a Polisario-held zone in a 1991 cease-fire between the Polisario Front and Morocco, which had been agreed upon together as part of the Settlement Plan. Morocco controls the areas west of the Berm, including most of the territory's population. The cease-fire is overseen by the United Nations' MINURSO forces, charged with peacekeeping in the area and the organization of a referendum on independence.