The most prominent language family of sub-Saharan Africa is the Niger-Congo family. Up to almost 1,500 separate languages are distinguished, belonging to a large number of sub-family level groupings. The exact hierarchical subdivision within this family is still under investigation, and different opinions compete with each other. However, the hypothetical common 'proto-Niger-Congo' ancestor is thought to have ceased to exist as early as 5,000 years ago. The largest of the sub-families is made up by the so-called Bantu languages, native to Central and the largest part of Southern Africa. Most numerous are Swahili with 5 million first language speakers in the East African countries, an additional 30 million using it as a second language lingua franca; Yoruba (20 million) in Nigeria and the eastern part of West Africa; Igbo (17 million) of Nigeria; Fulani (13 million including second language speakers) in West Africa, Wolof (2.7 million in Senegal, an additional 7 million second language speakers); Zulu (9.5 million) of South Africa, Lesotho, Swaziland and Mozambique; Rwanda (9.5 million) of Rwanda and adjacent countries; Lingala (8.5 million including second language speakers) of the Democratic Republic of the Congo, Xhosa (7 million) of South Africa and Lesotho; Shona (7 million) of Zimbabwe, Mozambique, Zambia and Malawi; and Akan (7 million) of Ghana.