Interesting. Some time ago I sold a similar knife. I bought it from a man who found it in Congo with the Kongo-tribe when he was working there in the late 50's. He told me it was a hunting knife. It's possible that these knifeblades were traded all over West- and Central-Africa.
The knife itself looks quite similar. Only the sheath differs. I would say your sheath comes from West-Africa (probably Mandingo).
The handle on my knife was made of bakelite, I think. Your knife handle looks more like horn.
Here are some pics of the knife I had :
