Prince of Persia was one of the first things which came to mind but yeah I'm pretty sure it's only desert themed at this point.
Spice Trade - old indie game about being a spice trader in 14th century Iraq. Graphics are stylized to look like medieval art. Never really got into it, but it was fairly popular on freeware game sites back when it was released.
This is pretty cool, but I just went on a pilgrimage and this holy man poisoned me for no reason and I died because the doctor didn't cure it. God dammit.
If you are up for something really old, Quest for Glory 2: Trial by Fire
What is it about, though?
Civilization 5 allows you to play as Darius of Persia and Harun al-rashid of the Ottomans. There's probably also Arabian civilizations in the earlier games.
Al-Rashid is the leader of Arabia in civ5. And no wonder, seeing how the historical figure died centuries before the emergence of Ottomans.
Oh, by the way, in the fantasy civ4 mod called Fall from Heaven, the Malakim civilization is modelled on the Arabian theme, complete with the world turning into deserts under their cultural influence.
The Malakim did come to mind when I was thinking of this, so I'll get around to that.
Anyhow... Medieval Total War 2 lets you play a Muslim country.
M:TW2 does let you be arab, but is there anything flavour-wise that makes it better than playing, say, eu3 as an arab country?
Keep them suggestions coming though!