Knife maders use various designs that are directed to the preferences of the market. Certain groups like the Bega and the Rashaida have specific preferences and the handle makers crafted specific designs to satisfy them.
Your knife is like what may be made for the upper Nile (north of Khartoum).
The consumer market isn't necessarily "tribal" in nature, but the style is regarded by most people in this area. The primary tribe in this area is the Ja'alin (see link below). Remember the blade, grip and sheath were made by different craftsmen in different sections of the market (suq). The makers may or may not have been members of this ethnic group. Also, each craft has a different status within the market and society.
https://en.wikipedia.org/wiki/Ja%27alin_tribe
I hope this helps,
Ed