The Bantu people originally lived in West and Central Africa around what is today Cameroon and Nigeria. Around 4000 to 3000 years ago they began a millennia-long expansion into much of the continent. This event has been called the Bantu expansion; it was one of the largest human migrations in history. The Bantu are believed to have been the first to have brought iron working technology into large parts of Africa. The Bantu Expansion happened primarily through two routes: a western one via the Congo Basin and an eastern one via the African Great Lakes.