The Bambara people I heard descend from a noble class of Mandinka people from the Mali empire. But man... The Mande people are so damn powerful in West Africa especially with the political clout they have. However, I wouldn't say everybody in West Africa descends from the Mande. If anything the region of West Africa was populated by different groups throughout different periods. But.... I have a theory that outside of Pygmy like groups(the original coastal West Africans) that the Mande and Fulanis were among the FIRST to reach West Africa from the Sahara after the drying of it especially from settlements like Dhar Tichit in Mauritania. There's actually theories that certain West African haplogroups like E-M2 originated in North Africa but that a story for another time. I believe West African groups like the Yoruba, Igbo, Hausa, Fon, etc are more recent.
From the research that I have seen the Yoruba are not recent. They are actually very old. I think that they maybe the oldest group in West Africa. I am not sure if the Fon are Yoruba, but I think that they might have some kind of genetic or historical connection to the Yoruba.
I seem to recall reading that the Hausa people are Chadic. So they are not even originally from West Africa. I read a research paper once that indicated that their language is very closely related to the language spoken in Kemet. So they might have Egyptian roots, which would might why Black people that take genetic tests will have some random strain from Sudan in their DNA results. That seems to point to their origin being in the Sahel.
I don't know where the Igbo people are from, but some people speculate that they are semi-Bantu. I don't know how true it is, but the Bantu migration seems to started from their region near the Nigerian and Cameroon borders.
Mande, Fulani, Serer, Wolof and Berbers are definitely Sahelian. Berbers are in North Africa as well, but their range is also clearly down into Sahel. All of those groups have very long history together. IMO the Akan, Ewe and Ga/Dagomba people histories are a little unclearer. Finally, genetic testing is really confusing the Hell out of people, because it is giving them some kind of phony modern State as an indicator of ethnicity rather than the actual ethnic groups that they belong too. Mande people for example extend all the way into Northern Nigeria just like the Fulani, but people are just getting Nigerian as a result and it is not clear if Nigerian is for those groups or for Yoruba, Igbo, etc. . . .