Spain gave up its Saharan possession following Moroccan demands and international pressure, mainly from United Nations resolutions regarding decolonisation.

In July 1885, King Alfonso XII appointed Emilio Bonelli commissioner of the Río de Oro with civil and military authority.

[3] In the summer of 1886, under the sponsorship of the Spanish Society of Commercial Geography (Sociedad Española de Geografía Comercial), Julio Cervera Baviera, Felipe Rizzo (1823–1908) and Francisco Quiroga (1853–1894) traversed the territory, which was called Río de Oro, and made topographical and astronomical observations.

[4] On entering the territory in 1884, Spanish forces were immediately challenged by stiff resistance from the indigenous Sahrawi tribes, Saharan Berbers who lived in many oases and coastal villages.

The indigenous people worked mainly in fishing and camel herding, and speak the Hassaniya language, a Bedouin Arabic dialect.

A rebellion in 1904 was led by the powerful Smara-based marabout, Shaykh Ma al-'Aynayn, was put down by France in 1910, which ruled neighbouring Algeria.

It forced some of the previously nomadic inhabitants of Spanish Sahara to settle in certain areas, and the rate of urbanisation was increased.

The Front's guerrilla army grew rapidly, and Spain lost effective control over most of the territory by early 1975.

Its effort to found a political rival, the Partido de Unión Nacional Saharaui (PUNS), met with little success.

[citation needed] In the winter of 1975, just before the death of its long-time dictator Generalissimo Francisco Franco, Spain was confronted with an intensive campaign of territorial demands from Morocco and, to a lesser extent, from Mauritania.

In the process of annexing the region, Morocco started fighting the Polisario Front, and after sixteen years, the UN negotiated a cease-fire in 1991.

[13] Under international law, Morocco's transfer of its own civilians into occupied territory is in direct violation of Article 49 of the Fourth Geneva Convention.