To expand on the reasoning behind the suggestion (for people not wanting to go between two threads), my suggestion was to make only the Sahara desert provinces actually desert, and all other desert "Steppe," because all of the other actual deserts (Rub al-Khali, Dasht-i-Kavir, Ustyurt, etc.) are one of the following:
- Impassable provinces
- Close enough to sedentary areas that you could argue they aren't as "harsh" since there are some resources available (Especially since a lot of current desert was more agricultural before the Mongols wiped whole civilizations out)
- Small enough in size that traveling through them would not be as much of a tax on resources (since CKII does not model supply chains/logistics)
This would let the Sahara be muuuuch harsher than it would be normally. And, it could help curb trans-Saharan empires, which really would not have been remotely feasible during the time-frame of the game (even up until the early pre-Modern period).
The map projection really shrinks the Sahara and in reality, it is much bigger than is currently shown. The small task of traveling through other deserts, while harsh, would have been nothing compared to trans-Sahara travel. That type of travel took months, was extraordinarily dangerous, and modeled poorly in-game.
Unless you guys can and want to create a whole new terrain type for the Sahara, I think it's a good idea.