The tracks in your iTunes library will be matched against the store in which you have an account. You don't explicitly say which store that is so for the sake of argument let's say it is the U.S. store (since iTunes Match is currently only available in the U.S. anyway).
During the initial scan of your library if the album by the South African band is available in the U.S. store, then it will be matched. If it is not available in the U.S. store then the files will be uploaded. ITunes Match does not scan other countries stores for matches. This will apply to all the music in your iTunes library.