…quite a lot of American-born converts (who can probably be roughly divided into "African-American" and "Other", but don't quote me on that).

Important note: “Black Muslims” (as distinct from Muslims who happen to be Afro-diasporic) usually denotes the Nation of Islam, which originated in the U.S. in 1930, is very much its own thing, and isn’t regarded as “real” Islam by more mainstream Islamic denominations.