There are numerous desert storage locations (deserts make pretty good aircraft storage environments, so yeah), but I'm going to assume that you mean the Aerospace Maintenance and Regeneration Center also known as The Boneyard at Davis-Monthan Air Force Base in Tucson, Arizona. You can read more about it here
. In short, the recycle and reclaim aircraft, refit aircraft for sale to friendly governments, and scavenge aircraft to support airframes still in service.
Many years ago, back when my dad was a kid living in Tucson, you could simply walk right into the boneyard. Not so much today.