By the way Thamis,
I have a new version of my resources mod out, so you might want to check that out and include some of that. For instance, there's a new Olive Oil resource, which would be very appropriate to this time period.
Also, have you seen the maps on my website? Tons of good maps there to help you figure out which resources were important, and where they were located.
http://apolyton.net/haven/
I saw your map for the mod. Better than the one I thought you were using, but still highly flawed. The map you're basing it on is inaccurate in many ways. For instance, the vegetation for that map is based from around 500 AD, when there was a lot less forest in this area. I have a better map for you to base yours off of, which I will email you.
And given that there's absolutely no Jungle or Tundra in your map, I was thinking you may want to rename them and use them for something else.
I've been told that when one gives a terrain type a food value of 0, the AI will not build cities on it, except along the edges (or if there are big food resources in the area). So if you want to prevent cities in the Sahara, that should take care of that. I see your latest rules has Desert give 0 food- has anyone noticed if that has helped? Giving desert no Irrigation would also help I think.
Given that Tundra can have forest on it, I suggest you rename it Evergreen, and put only forest with the "pine" appearance on it. On all other forests, never use the pine appearance. So this way, all you have to do is change the underlying terrain graphic with something else and you have a new terrain type.
There are a number of different things you could do with Jungle. Sand is one, another good idea would be Swamp.