Hi Iain,
Just a feeling - I would allocate it a little bit more to the west from the North Cameroon (baldric, style of braiding on the handle /?/). You can find very simmilar sword (blade) on this nice web:http:
www.africanarms.com. Also, they used very simmilar, localy forged - but new, narrow and thick blade on this Mandingo sword.
Regards,
Martin