According to paleoclimate models and scientific discoveries in the region, the desert dried out through a gradual climate change well over five thousand years ago. It was once much like the Sahel region to the south, with dry grassland and seasonal lakes.
Because the land is arid and has a very little amount of rain fall, making it extreme for survival.
This means that animals and plants must adapt to cope with the conditions.
10 000 years ago the Sahara had grass and other vegetation with plenty of wild animals and the climate was moderate. Approximately 4000 BC there was a dramatic change in climate and the rainfall became less. This lack of rain caused the rivers and lakes to dry up which led to soil erosion. The Sahara is the largest desert in the world with an area of 9,1 million square kilometers.