Were there significant crops in central Africa during the Middles Ages, that is, during the period from 600-1450?

What about trade and commerce or labor systems?

Please provide me references. Thank you so much!

Three of us extensively researched this question yesterday and didn't find much. The basic problem is that since central Africans didn't have a written language during that time period, very little is known about their lives then. Check the answers we posted yesterday:

http://www.jiskha.com/search/search.cgi?query=central+Africa