The largest desert on Earth
stretching from the Atlantic Ocean to the Red Sea on the Africa
n continent. Countries which lie within the Sahara Desert are Morocco
, and Sudan
. The Nile
River and the Niger River
cross through it.
Scientists believe that 4,000 years ago the Sahara region had a much wetter climate with a savanna
environment. The tilting of the Earth's axis
caused an abrupt change in climate
(such as more sunlight and an amplified monsoon
season) causing the desertification
of the Sahara region.