Moroccans march into Western Sahara in the Green March, 1975
Ever since gaining its independence from Spain in 1956, Morocco firmly held that the Spanish Sahara (now known as the Western Sahara) should be included within its borders. Morocco based this assertion on the fact that some of the nomadic populations in the region had apparently once owed allegiance to the Moroccan sultan, yet the strength of its commitment to securing control over Spanish Sahara may have increased after it became known in the early 1970s that the region contained substantial phosphate mines.