Right. The Sahara Desert use to be green at one time.
I find shells and fossils in the desert here, indicating that it was once wet and green.
Discussion
yeah, desertification, i'm pretty sure the primary cause is low flying meteors and airbursts (like the one that flattened Tunguska), as it burns the carbon in teh soil, which is what makes soil fertile and able to hold water
there is ancient stories about giant fire dragons fighting in the sky, that's what these relate to, these things get so hot that if you are too close to them you are flash-incinerated