From the Super Mario Wiki
Desert Hills is a race course in Mario Kart DS. Pokeys roam around the desert, and the Angry Sun will drop Fire Snakes on the track (on the DS version they're just fireballs) at three different places (one is in front of the starting line, and the other two are on twisting turns on the track). The course has many sharp turns before the finish line, possibly resulting in driving onto the sand, losing time. Missions 2-6 and 4-4 take place here, where Wario participates in both of them.
There is a considerably shortcut in this course, taken by going straight across the hairpin turn, instead of going around. In 150cc, this shortcut requires only one mushroom, if the player jumps at the right time. There is also another, where two mushrooms (or one star) is needed to get through. This shortcut is a dash-through behind the pyramid, right before the Pokeys start appearing.
Desert Hills appears as a remade classic track in Mario Kart Wii, being the first racecourse of the Leaf Cup. No real changes had been made in the track after its first appearance, other that the Pokeys are no longer flat and karts don't flip when making contact on them. Instead of that, they just spin around. Also, the course map has been rotated 180 degrees in contrast to its predecessor.
The track starts near an oasis with a small lake where a racer can sink in the water, bringing Lakitu for the rescue. To the right of the first turn, the track partially surrounds a pyramid made out of Brick Blocks while racers leave the oasis to find then a field of dunes infested of Pokeys sliding to the sides of the course. Just before the finish line, a curly path of soft sand will cause karts (especially those with high drifting) to lose a bit of control, ending up on going to rough ground zone and lose speed. The Pipes, Angry Sun, and blocks are the same of Super Mario Bros. 3.
There are two missions involving this circuit: 2-6 and 4-4.
In mission 2-6, the player must use the Bob-ombs to destroy 5 pokeys, and in mission 4-4, the player must pass the 7 gates in the order.
 Official Description
Instruction Booklet: This racetrack built in the middle of the desert tends to be quite bumpy.
 Mario Kart DS
 Mario Kart Wii
 Names in Other Languages