The Sahara is by far and away the largest desert on earth. But that wasn't always the case, the massive (and strange) dinosaur Spinosaurus's fossils have been found in the Sahara by what were once rivers and swamps. But one doesn't need to go back 99.5 million years ago to find a green Sahara - less than 10,000 (or even 6,000) years will do nicely.

Cave paintings and rock art from between 14,600 and 5,000 years ago show us that the Sahara was a very different place. For the really adventurous travelers out there, cross the Sahara by land! It is incredible and quite easy along the coast of Morocco.

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The African Humid Period

This period of a green Sahara is known as the African humid period (together with other names). It was a climate period in Africa that lasted from the late Pleistocene and Holocene geologic epochs. During this time northern Africa was much wetter than today. Much of what is now desert was covered by grasses, trees, and lakes.

The shift in climate was caused by changes in the Earth's orbit around the Sun.

  • The Sahara: The Largest Desert In The World Today

During the preceding last glacial maximum the Sahara was mostly uninhabited and was much larger than today (even Lake Victoria may have been dry).

The African Humid Period began around 14,600 years ago and the Sahara went into dramatic retreat up until around 6,000 to 5,000 years ago. Lake Chad swelled and glaciers grew on Mount Kilimanjaro.

  • Duration: Around 14,600 to 5,000 Years Ago

Related: Join The Bedouin And Go Camel Riding In Morocco

What The Sahara Was Like

With the increased water came the grass, with the grass came grazing animals, and with grazing animals came the hunters - like humans. In this period, the Sahara was widely settled (and even is reputed for helping give birth to the Pharaonic civilization).

  • Animals: The Sahara Was Full of Animals Who Can't Live There Today

These people had left behind many archaeological sites with many rock paintings. These hunter-gatherers painted what they saw around them. While anyone there today will only see desert, they saw giraffes and many of Africa's famous wild animals. As the period ended, humans (and other animals) gradually abandoned the again inhospitable desert.

  • Hunter-Gatherers: Depicted What They Saw Around Them

Today the Sahara is a sparse and inhospitable land, but it is full of incredible surprises. Some of the Sahara's treasures can only be appreciated from above.

For those who would like to see some educational 8-minute videos on when the Sahara was green, one can watch the British Museum's Rock Art in the Green Sahara, or PBS Eon's excellent When the Sahara was Green.

Related: What You Should Know About Visiting Marrakesh And Why It's Worth It

Some Notable Caves In The Sahara Depicting A Different World

Cave Of The Beasts: This is a large natural rock shelter in the Western Desert of Egypt with Neolithic rock paintings. Today it is in one of the driest parts of the Sahara but during the African humid period it there was a lake at the foot of the shelter. Paintings are thought to be over 7,000 years old.

  • Located: In the Libyan Desert In Southwestern Egypt
  • Animals: Include Elephants, Ostriches, Gazelles, and Giraffes (Don't Exist There Today)
  • Number: Around 5,000 Figures
  • Date: About 7,000 Years Ago

Cave Of Swimmers: The Cave of Swimmers is located very close to the Cave of Beast above. Both are in the Gilf Kebir area of Egypt

  • Located: In the Libyan Desert In Southwestern Egypt
  • Animals: Includes Giraffes and Hippos (Don't Exist There Today)
  • Date: Around 10,000 Years Ago

Tibesti in Chad: Located in the Tibesti Mountains In Chad today in the central Sahara. These mountains are renowned for their rock and parietal art and so far around 200 engraving and 100 painting sites have been identified.

  • Located: In Chad
  • Animals: Includes Elephants, Rhinos, Hippos, Giraffes, Ostriches, Baboons, and Others
  • Date: Between 12,000 and 4,000 Years Ago

Tamanrasset, Algeria: These depict vivid scenes of everyday life in central North Africa. There are over 15,000 individual pieces of artwork here and including both paintings and engravings of African culture of as much as 12,000 years ago. It is a site where new artwork is still being discovered.

  • Animals: Rhinos, Elephants, Hippos, Giant Buffalo
  • Date: 10,000 to 6,000 Years Ago

Visiting Today

Unfortunately, almost by definition most of these sites are very remote and are often very difficult to get to. Some are in remote and dangerous regions of unstable countries (there are travel warnings out for Chad and Libya).

It may be possible to find tours or specialty tours in countries like Egypt and Algeria, but these are likely to be custom and expensive. Western Desert Tours may be able to provide tours out to the Cave of the Beasts area.

Next: 10 Breathtaking Desserts You Need To Walk Across On Your Next Trip!