It would be a good variation for Machaka methinks. Raise the heatscale to +2, since this reflects the desert heat.
I'm not sure the whirling dervish is a good choice for sacred unit. Wrong culture perhaps? But then again I know so very little about arabian myths and legends.
Same thing with Viziers. Weren't they part of the caliphate administration? Perhaps just a name change is all that is needed?
I don't think a Reader of the Sands ability would be possible in Dominions 2. But as a plain cheap assassin in would be great.
Courtesan sounds a bit... Errh... Hard on the suspension of disbelief? Surely it takes more than a pretty face to turn highranking commanders against their former allies? Then again it might be my annoyance for the "seduce" ability talking. I liked it even less in Age of Wonders. Perhaps give this unit both spying and assassination abilities instead?
Just one summoned unit?
There a tons of cool mythical creatures to be found in this setting.
The nation seems to be a cross between Pangea and Machaka. It should work very well, since the concept is well balanced. A suprising lack of archers though.