I played in Sartar for years. It was quite easy to imagine chat could be opponents in adventures in Sartar and Prax : Broos, scorpionmen, Tusk rider, all other haos, prax tribe, Undead in the marsh, Lunar, bandits, ...
But I have more difficulties finding this in Umathela : Lascerdans are dead, Vadelis are defeated, no chaos, ...
Then except a skirmish from Orlanthi tribes, what can give challenges to the PC (on the combat side I mean)? What are the big threats, monsters, dangers?