Biafra was/is a kingdom to the then Western Ethiopia or North Congo, whose according to the history books the then original capital city of the same name was sited about six miles up Wouri River in what is now Cameroon-a position which coincides with Douala. There are fairly detailed accounts of Biafra both in O.Dappers "Description de l'Afrique" published in Amsterdam in 1686, and in John Barbot's "A description of the coats of North and South Guinea (in the 5th vol of "A collection of voyages and travels" published by A&J Churchill in London in 1732). It was in the days of the late 1950's foreign opponents of Cameroon reunification debunked Biafra as a myth to put off Cameroon nationalists. (See Bouchauld "La Cote du Cameroun dans l'histoire et cartographie"). But how can one explain the maps of the 17th century which speak of a "Regnum Biafrae" which extended over a great part of central and coastal Cameroon, and that in 1732 Barbot spoke of Biafra in the same breath as Benin, Ashanti, Gabun and the Ambozes (from which comes Ambas Bay, on which stands Victoria, West Cameroon)? As these names are indigenous there is no reason why "Biafra" should not have been the indigenous name, but should have been coined by the Portuguese. Archaelogical evidence came to light on the ancient existence of Biafra and/or Agysimba in 1966 in Cameroon.
The picture I have included here is the French chart of West Africa 1780, titled River Senegal to Biafra.