There's around half a million nomads and desert dwellers. Biggest city is 15k or so.
Call me a world buliding nerd, but ... where does the food come from? I didn't know you where using a pre-made setting, but I personally find sketching out the
economy of an area is great inspiration for how players interact with it.
Not because the economy is usually important, but because thinking about it adds a structure to hang a story on, and it adds Verisimilitude to the plot (it feels less like the thing was added as an adventure hook, instead of it being a hook into something that was naturally there).
...
Another way to approach this is to make a flowchart "dungeon".
Start with a few spots/scenes.
Oasis
Oak Tree
Gateway City
Central City
Grand Bazaar
The Deep Desert
Caravan
On the Sandy Seas
Ancient Cave
Salt Flats
Toss down ideas of what could be in an encounter there
Oasis - Nomads, Sandstorm, Sand Shark, Oak Tree
Gateway City - Guide, Rival Searchers (Fantasy Fascists?), Join a Carvan, Market
Central City - Pirate Market, Scholar, Market, Freedom Fighters
Grand Bazaar - Thief, Rooftop Chase, Fortune Teller, Buying a Macguffin
The Deep Desert - Sand Sharks, Nomads, Sand Worm, Warforged
Caravan - Thief, Fantasy Fascists, Fortune Teller, Raiders
On the Sandy Seas - Sand Pirates, Sand Sharks, Walk the Plank, Breakdown, Privateers
Ancient Cave - Paintings, Warforged, Undersand (underdark equiv), secret word to open door, magic lamp
Salt Flats - Miners, Fantasy Fascists, Sand Boats, Salt-preserved Vampires, corrupted water elemental creatures
Build a graph connecting them, with just a sentence describing connections. That can spawn new events at each node.
Have reasons to leave nodes with disaster behind them (like, you steal a macguffin in city 1 and flee the watch). And have reasons to
backtrack at least once, so you get to see the results of your past actions.
We need reasons to move around; mini-macguffins. The Pirates knowing something, as does the Scholar, the Salt Miners, the Warforged. The rival group (Fantasy Fascists) trying to do the same thing and getting in the way -- in Indiana Jones movies they tend to use Indiana as a way to get information. Invert that trope and have them leak like a sieve, so the players use
them to get information about what to do next?