How did geography affect trade in West Africa?

That is a tough question to give a straight answer to. I hope you know that Africa is a continent. Africa has one fifth of the world's land, one sixth of nations, and one seventh of population. Africa is this big: kai.sub.blue/images/true_size_of_africa_v3-da3dd38e.jpg

Now you ask about geography. What exactly do you mean by that word? Geography could be anything from a single rock to a mountain range. Likewise, what is West Africa? That might take in twenty or so nations.

You need to focus your question a little better than that.