Niger Delta is a very densely populated region sometimes called the Oil Rivers because it was once a major producer of palm oil. The area was the British Oil Rivers Protectorate from 1885 until 1893, when it was expanded and became the Niger Coast Protectorate. The delta is a petroleum-rich region, and has been the centre of international controversy over pollution, corruption (notably by the Abacha regime), and human rights violations.
The Niger Delta, as now defined officially by the Nigerian government, extends over about 70,000 km2 (27,000 sq mi) and makes up 7.5% of Nigeria's land mass. Historically and cartographically, it consists of present-day Bayelsa, Delta, and Rivers States. In 2000, however, Obasanjo's regime included Abia, Akwa-Ibom, Cross River State, Edo, Imo and Ondo States in the region. Some 31 million people of more than 40 ethnic groups including the Bini, Efik, Esan, Ibibio, Igbo, Annang, Yoruba, Oron, Ijaw, Ikwerre, Itsekiri, Isoko, Urhobo, Ukwuani, Kalabari, Okrika and Ogoni, are among the inhabitants of the political Niger Delta, speaking about 250 different dialects.
The Niger Delta, and the South South geopolitical zone (which contains six of the states in Niger Delta) are two different entities. The Niger Delta separates the Bight of Benin from the Bight of Bonny within the larger Gulf of Guinea.
The core Niger Delta later became a part of the eastern region of Nigeria, which came into being in 1951 (one of the three regions, and later one of the four regions). The majority of the people were those from the colonial Calabar and Ogoja divisions, the present-day Ogoja, Annang, Ibibio, Oron, Efik, and Ijaw peoples. The National Council of Nigeria and Cameroon (NCNC) was the ruling political party of the region. The NCNC later became the National Convention of Nigerian Citizens, after western Cameroon decided to separate from Nigeria. The ruling party of eastern Nigeria did not seek to preclude the separation and even encouraged it. The then Eastern Region had the second, fourth and fifth largest indigenous ethnic groups in the country including Igbo, Efik-Ibibio and Ijaw.