Based on dental evidence, Joel D. Irish of Liverpool John Moores University suggests sub-Saharan West African affinities for the Kiffians, in turn suggesting that the common ancestors of West African and Proto-Bantu peoples may have originated in the southwestern 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.[4] From parts of southeast 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.[4]