Bantu expansion
Theories on expansion

Bantuists believe that the Bantu expansion most probably began on the highlands between Cameroon and Nigeria. The 60,000-km Mambilla region straddling the borderlands here has been identified as containing remnants of "the Bantu who stayed home" as the bulk of Bantu-speakers moved away from the region. Archaeological evidence from the separate works of Jean Hurault (1979, 1986 and 1988) and Rigobert Tueché (2000) in the region indicates cultural continuity from 3000 BC until today. The majority of the groups of the Bamenda highlands (occupied for 2000 years until today), somewhat south and contiguous with the Mambilla region, have an ancient history of descent from the north in the direction of the Mambilla region.

Initially, archaeologists believed that they could find archaeological similarities in the region's ancient cultures that the Bantu-speakers were held to have traversed. Linguists, classifying the languages and creating a genealogical table of relationships, believed they could reconstruct material culture elements. They believed that the expansion was caused by the development of agriculture, the making of ceramics, and the use of iron, which permitted new ecological zones to be exploited. In 1966, Roland Oliver published an article presenting these correlations as a reasonable hypothesis.

The hypothesized Bantu expansion pushed out or assimilated the hunter-forager proto- Khoisan, who had formerly inhabited Southern Africa. In Eastern and Southern Africa, Bantu speakers may have adopted livestock husbandry from other unrelated Cushitic -and Nilotic -speaking peoples they encountered. Herding practices reached the far south several centuries before Bantu-speaking migrants did. Archaeological, linguistic, genetic, and environmental evidence all support the conclusion that the Bantu expansion was a significant human migration. Generally, the movements of Bantu language-speaking peoples from the Cameroon/Nigeria border region throughout much of sub-Saharan Africa radically reshaped the genetic structure of the continent and led to extensive admixture between migrants and local populations. A 2023 genetic study of 1,487 Bantu speakers sampled from 143 populations across 14 African countries revealed that the expansion occurred ~4,000 years ago in Western Africa. The results showed that Bantu speakers received significant gene-flow from local groups in regions they expanded into.

Based on dental evidence, Irish (2016) concluded that the common ancestors of West African and Proto-Bantu peoples may have originated in the western region of the Sahara, amid the Kiffian period at Gobero, and may have migrated southward, from the Sahara into various parts of West Africa (e.g., Benin, Cameroon, Ghana, Nigeria, Togo), as a result of desertification of the Green Sahara in 7000 BC. From Nigeria and Cameroon, agricultural Proto-Bantu peoples began to migrate, and amid migration, diverged into East Bantu peoples (e.g., Democratic Republic of Congo) and West Bantu peoples (e.g., Congo, Gabon) between 2500 BC and 1200 BC. He suggests that Igbo people and Yoruba people may have admixture from back-migrated Bantu peoples.
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