I have the words and music of Si Si Si in a book called "How can I keep from Singing" (British Kodaly Academy) which gives it as Congolese. The word Banaha does occur in the song, but it shouldn't be confused with Ban-u-wa, which is in the same book, Ba-nu-wa is cited as Liberian and is a nine part round!

You can sing Si Si Si as a round, or as a two part harmony song or both!!
Best wishes
Saro.