|The following information is from the Adventure Time comic book series.|
It may not be part of the same canon or continuity as the animated series.
The Desert Kingdom is the land ruled by Desert Princess. In Issue 1, it was pulled into the Bag of Holding by the Lich. Finn and Jake meet Desert Princess in it shortly after being pulled into the bag. The kingdom's terrain is sandy and has a lot of plateaus. Skeletons can be seen scattered across it. By the end of Issue 4 all the sand leaked out of the bag after the fight with the Lich and covered all of the Land of Ooo. Finn and Jake then asked Desert Princess to use her powers to put all the sand into the crater caused by the Mushroom War. With all of the sand now in the crater, Water Princess uses her powers to give the new kingdom a lake. Once finished all of our heroes are seen celebrating both the defeat of the Lich, the birth of a new kingdom and the expansion of Earth.