On stats: I wouldn't give them higher sterngth - after all, classic barbarian unit is straight from Conan the Barbarian, & in this mythos desert nomads are wiry & fast, not particularly strong.

Better defense is fine & it's along these lines. AP 13 is probably okay, remembering "running back & forth" mentioned above (btw you were partly right, it's Mohammed who introduced phalanx-like formations here, though they probably seen something before serving as mercs during Persian-Byzantine wars). Higher MR can be explained by genie influence & the fact that genies were certainly not above mixing their blood with that of subject folk...

BTW this could explaine higher stats of your "dervish" pretty well!

Though gold cost is probably going to be 11? Rukh - I would think it summon, but understand your reasoning on summonable eagle (I tried it once & never used since!

) - for usefulness we can remember that Roc/Rukh was said to hunt elephantes & give it better attack against large creatures (not sure how it works, though) or something along these lines (& you surely can imagine what it would be to be near such birdie than it starts to beat wings, so trample isn't completely out of question... or swallow).
Also, on the desert garb - did you remember that 'furs' also give defense & encumbrance penalty which desert garb shouldn't do?
On .dm - probably genie nobility should get something richer than leather cuirass?

Even "magical lightweight armor"

possibly?
on MA - for now it looks about this:
units: Nomad infantry, Nomad cavalry - both armored,etc. as above, probably stealthy (in this case, got "raiders" in their name);
Deilemite (mountainmen) infantry - light armor (see which), large shield, javelin, probably their authentic jupine (2-end spear

) or axe/bardiche/halberd, better morale;
Corsairs - 2 scimitars, probably leather cuirass (these don't wear desert garb!), pillage bonus;
Faris (Arab noble cavalry) - standart noble stats boost, light lance, chain hauberk, probably thrown axe or javelin;
Ghulam cavalry - full scale, composite bow, scimitar or broadsword (they almost never used lances);
Nomad ahdas (militia) - purhased for 1 battle, so cheaper, stats are as normal;
Ghazi - sacred, probably both infantry & cavalry; probably Ghulam/Mamluk infantry;
slighly possible elephant or nafta throwers (both were used in the region, but relatively rare = if make, then capital only). Maybe add some more regular infantry such as citizen militia?
Commanders:
Nomad chieftain (stealthy, I think, but with Ld 40);
Corsair captain (?) - sailing, of course!;
Pekhlevan - noble with genie blood, so larger than human, much stronger, with some random(?) magic;
Imam (priest 2), Kadi (priest 2 with patrol bonus/decrease unrest), Hoji (priest 3, capital only?), possibly Khalif as a highest priest (4) with fighting ability & Ld 40; possibly capital-only Ismailite priest?
Amir or something as regular troops commander with Ld 80;
Star-gazer - Astral 2 mage, prevent bad events;
Elemental sorcerers of at least 2 kinds (normal and higher, need to think that up);
Thief of Baghdad/Xanadu - spy (unfortunately, engine doesn't allow him to be used to steal, e.g., opponent's gems

);
Hashishiine - names says all.
Genies become summons in this era, except possibly some minor one...