Bantu peoples
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 BCE. 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 BCE and 1200 BCE. He suggests that Igbo people and Yoruba people may have admixture from back-migrated Bantu peoples.