A common mistake when writing adventures set in deserts is to assume that the climate is too ferociously hot to wear armor. Historically, most battles in deserts involved troops dressed in protective armor. Although they would have been miserable during the hottest part of the day or the hottest part of the year, desert weather isn't intolerably hot 24/7.
A legend tells of a people living deep in the desert, they appear at first as ordinary human beings, sometimes impersonating someone familiar to the PCs, before causing their features to disappear, leaving a blank, smooth sheet of skin where their face should be.
A civilization which constructs of irregular shapes constructed of a light metal, heaped together so that they stand on each other; these structures rattle and bend in the wind or at a push, but ultimately hang together except under heavy force (such as cannonballs, falling stones, floods)