Rio Muni was ceded by Portugal to Spain in 1778. The Spanish had hoped to collect slaves to work in their other overseas possessions, but their settlers died of yellow fever and the area was deserted. Cocoa and timber became major industries upon recolonization. Rio Muni became a province of Spanish Guinea along with Bioko in 1959.
Rio Muni currently has a population of about 300,000, mainly composed of ethnic Fang tribes. It is split into four political jurisdictions: Centro Sur, Kie-Ntem, Litoral and Wele-Nzas. The largest city is Bata. Other major towns include Evinayong, Ebebiyin, Acalayong, Acurenam, Mongomo, Sevilla de Niefang and Mbini.