Even though Afro-Diasporans will usually trace their African roots exclusively to areas within Western, Central and Southeast Africa, these subregions of the African continent are already enormously diverse in ethnic groups and languages! No doubt all this overwhelming variation complicates finding out exactly which ethnic lineages you might hail from. However learning more about the bigger ethnolinguistical groups can be helpful to get a better grip on your regional origins at least and also make more sense of any DNA testing you might have done.
Probably the most detailed ethnolinguistical maps online can be found on the amazing muturzikin website. I will not repost them here, but you can find the ones for Africa yourself via this link (scroll down for the country maps): http://www.muturzikin.com/carteafrique.htm.
Another great online resource of African maps can be found via this link: http://worldmap.harvard.edu/africamap/. It enables you to choose from many different overlays drawn from different datasets and themes.
This map below should also be useful even though it’s far from complete in listing all ethnic groups; if you click on it you can see the enlarged version!
Basically most Afro-Descendants will have African ancestors who spoke a language belonging to the socalled Niger-Congo language family. This language group consists of hundreds if not thousands (also counting dialects) related but distinct languages spoken by as many ethnic groups. To simplify things usually the first distinction being made is between Bantu languages from Central and South/East Africa and non-Bantu languages from West Africa. The Bantu languages are assumed to be more recent because of the socalled Bantu migration and therefore also more interrelated than the various West African language subgroups. The names and definitions of these West African language subgroups tend to change so that’s why i included several maps below.