They traded items like ivory, wooden sculptures, animal skins, spices, cotton, food products and many more.
This is a fact.
Please see the articles below:
1)
https://www.livescience.com/benin-bronzes-were-crafted-of-metal-from-a-completely-unexpected-place
2)
Benin Bronzes are made of German brass
https://www.eurekalert.org/news-releases/984344