In 1778, Queen Maria I of Portugal and King Charles III of Spain signed the Treaty of El Pardo which ceded the Bioko, adjacent islets, and commercial rights to the Bight of Biafra between the Niger and Ogoue rivers to Spain.
At the beginning of the 20th century, the plantations of Fernando Po were largely in the hands of a black Creole elite, later known as Fernandinos.