The Sahara desert in Pre-Colonial Africa was once supported life when it was rich in vegetation and animal life.
The story of how the fertile green Sahara supported vegetation and animal life became a desert spans 40 million years.
In that time, the green Sahara lost its vegetation and animal life, transforming from Ocean to desert.
The history of how the fertile green Sahara lost its vegetation and animal life to become the barren Sahara desert dates back to about 40 million years ago when the Northern tip of Africa was submerged in an Ocean.
These Oceanic waters of the Sahara were the home of ancient vegetation and animal life supported in the Oceans of the Sahara.
Fossils of whales and sea shells discovered in the Sahara desert from this period suggest that the Sahara supported life when it formed part of a fertile green sea bed full of vegetation and animal life.
Then about 3 million years ago, the Ocean water levels fell, and the Sahara desert landscape emerged which lasted until 90 000 years ago when a shift in the Earth’s tilt would turn the Sahara green once again to enable it to support vegetation and animal life.
At this point, great lakes which would later form the great Lakes of East Africa like Lake Tanganyika were formed as the environment also shifted and a Savannah landscape that could support vegetation and animal life emerged from the fertile green Sahara.
This period also marked the establishment of a pattern in the Earth’s tilt that would shift the Sahara Climate from fertile green to desert every 20 000 years, and its also in this period that traces of Cave Paintings by early Hunter Gatherers whose lives were supported by the vegetation and animal life in the Sahara desert region. 
The last 10 000 year cycle in which the Sahara climate shifted to bring about changes in the vegetation and animal life of the fertile green Sahara resulted in the mass migration of early man from the fertile green Sahara to create the Nile Valley Kemetic Civilization which would eventually lead to the rise of Ancient Egypt.
