Hi Lew,
Thats a beauty allright!! Wow!!
This appears to be of the form often seen from Northern Sudan, most likely Dongola region (between 3rd and 4th cataracts on the Nile). It seems that these typically had an unusual drooping 'T' handle type pommel contrary to the form on this one, however the blade shape seems consistant. The 19th century examples typically, at least the ones I have seen, had a blade motif focused on a centrally located crocodile seen from above, along with geometric designs. Yours has interesting geometric designs which the central motif may well be highly stylized interpretation of the crocodile.
The hilt and highly stylized, cross hatched geometric designs seem to suggest this is likely into the 20th century. These weapons have remained highly important accoutrements among Sudanese men, much in the same manner as the janbiyya in Arabia, and are highly valued as symbols of manhood. Extremely nice example!
All the best,
Jim