I do not get what the Desert Sender is about.
I dunno either. I just thought it'd be cool to have something dune-ish. Sandworm commander? A guy that rides war elephants? Snake charmer? :P
Sorta all those things combined. Probably will just be a druid or ranger variant.
Oh yeah, that's as far as I'd take magic.
Or maybe there could be Bedouin Desert Rangers? I have just heard some war stories about Bedouin soldiers that would chill you to the bone. They notice things that everyone else misses. I do not know if this is playable, but hey, I am just pitching. You are the mastermind
Ah... I know nothing about the bedouins (I barely know about the teutons, excepting AoE2). :/
I hope you can see, I'm gonna need a lot of research before the world gets fully fleshed out. Mostly worried about detailing towns rather than greater threats right now.
Most of the baddies for any starting campaign will probably just be like random horrors, desert bandits, cults, the odd raider from the steppes or other far lands, etc.
Considering the eastern theme, most such games begin with players playing the role of travelers of far lands, usually having arrived at a town. It's easier that way to explain away things like cultural divide and the fact that hardly anyone in a town may help a PC if he's injured, ie. (until he makes them happy with a sidequest, heh). Regarding NPC hospitality - sure, they might invite him into their home, but chances are that they won't treat his wounds properly, etc.
(perhaps replacing Battle Rage?)
Maybe they can set traps better? I suppose they could also fill the roll of the animal tamers of this game - they haven't got as many weapon proficiencies, so they would otherwise find a lot of situations where they feel useless without the right pet; it's easier to have a character that smashes enemies to a pulp as well as tames animals, then simply 'smashes enemies to a pulp'. :P
The 'notice things that others miss' already applies to the dwarf and elf races, so it's not too hard to modify. That doesn't need to be an underlying theme though, I don't think (no offense). They could also be navigators - but I dunno if that's necessary. A survival game where players can only navigate the desert by night would be cool (night time is when they chart and plan a course of travel, set watch and then sleep; and in the morning, they don armor and set out again; in the hopes that there's no sand storm or the water runs out or a blue dragon doesn't sprout up from the ground, because blue dragons can swim underneath sands in this world).
I suppose players could be a part of castle sieges as well (there were plenty of middle eastern castles).
Various enemies include the teutonic horror of old country (I suppose it'd be hard to get away from the crusader theme; these guys are by no means unstoppable - they just wear heavy armor, technology that's superior in certain ways to that of sands, and the sands tend to have tech that's superior in other ways - and the teutons (needs another name, obviously) tend to be well prepared), and there's also the vikings and steppe peoples.
There's also free imperial cities that are feeling uppity and their local emperor (shah?) wants to declare war and raid some town or other.