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. 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".