According to a different source, this question refers to the text "Desert Racing."
The 4 Deserts Ultramarathon Series is a series of races that take place in four different deserts around the world. These include the Gobi Desert (western China), the Atacama Desert (Chile), the Sahara Desert (Egypt) and Antartica.
This text explains the particular difficulties that each race presents. The Atacama Desert, for example, is the driest hot desert in the world. The race in this desert starts high up, at 3,000 meters, and takes runners on several ascents and descents. Moreover, runners face loose rocky terrain.
On the other hand, the main challenge of the Sahara Desert is the fact that this is the world's hottest desert. Moreover, this desert has sand dunes that can reach 590 feet high. The main challenges of this desert are staying hydrated and battling exhaustion.