Nice set.
I think this set is from the Luba-tribe. I looked in two books :
Dodelijk mooi (Deadly beauty) and
Ijzerwerk van Centraal-Afrika (Ironwork from Central-Africa.
The information I got out of these two works point to Luba. In the first book a drawing shows a bow with similar pieces of wood at each end.
The second one shows some drawings of different forms of arrowheads, similar to the ones you have.
Nevertheless, in the book
Waffen aus Zentral-Afrika (weapons from Central-Africa) a similar bow is depicted, attributed to the Yaka.
So, I'm confused now.
I know that a recently a book was published on African arrows. I lost the title, but perhaps another forum member has it and can help.