This western African country includes both mainland territory and a number of islands. The indigenous Pygmy population was supplanted by various peoples from about the 1600s on. The Portuguese explorer Fernando Po came to the islands in 1473 and the area remained under Portuguese control until 1778, when it was relinquished to Spain. Development, however, was sparse under the Spanish, with the exception of plantations devoted to the production of cocoa. The region was accorded the status of a Spanish province in 1959 and at this point, investment from the mother country made Equatorial Guinea's population one of the most prosperous and well-educated in Africa. Granted autonomy in 1963, independence followed in 1968. The country's first president banned opposition parties two years later and in 1972, made himself president for life. His rule by decree was marked by a reign of terror such that at least a third of the population was killed or exiled. Nigerian workers, who had long formed the backbone of the plantation economy, were expelled (along with other foreigners) in 1976, a move which proved ruinous to the once-healthy economy. In 1979, a military coup overthrew the dictator, who was subsequently tried and executed. The new leader, a lieutenant colonel named Teodoro Obiang, sought to improve relations with Spain. New constitutions were approved in 1982 and 1991. Economic recovery hopes have been buoyed by the discovery of oil reserves.