'You can't just run around killing goblins and looting temples, this isn't the old days my boy. To make it today you've got to be part of the guild, and you need a team, and a look, and most importantly you need a manager. Like me.'
The desert is a curse from the Water God upon the wicked people who live in the South.
Said people offended the Water God in some way, and so the Water God placed water-trappers, bizarre, water-sucking beings, in the soil, and within years, the wilderness became a desert.
Thus, the desert folk shamans have special powers that allow them to find water-trappers so that they can be dug up and their water harvested.