Hi Russel,
As mentioned off-site, I believe this to come from the general region ranging from the southern Sudan to Tanzania, though this is based solely on the similarities to shields attributed to various tribes within that (rather large) region, with regards to the waisted shape and the use of a hide that appears to be the same as used by varius tribes in East Africa (Hippo? Rhino?).
I'll be looking foward to hearing what Iain and some of our more learned African specialists have to say.
Cheers,
Chris