Maybe so but right now I can only get there by land and it takes like 20 turns to do it. 10 or so of those turns I am just walking and not making any money. (but honestly I have never been there and not sure my merchants that are heading there now will make it over land. I know they can't by sea.) So while I might make more money per turn in Timbuktu I have to factor in the opportunity cost of travelling there and not making money while in transit when I could be sitting on gold in Venice and perhaps picking off a few enemy merchants while doing that.