I have to ask what is so technically beyond African metal work. Benin would have continuous European contact but above all highly skilled court artists. Look at the work in these links-
http://www.vikingsword.com/vb/showthread.php?t=12015
http://www.vikingsword.com/vb/showth...light=trumbash
These would be like the back woods compared to Benin.
I could bring up many examples from the archive of the most excellent African work.