The Sahara Was Once Green — Then Everything Changed

Today, the Sahara is the largest hot desert on Earth — a vast landscape of sand, dust, and extreme heat. But thousands of years ago, this same region looked almost unrecognizable. Lakes stretched across the desert. Rivers crossed the landscape. Grasslands supported wildlife, and human communities lived beside water in places that are now among the driest on Earth. This period is known as the African Humid Period — a remarkable chapter in Earth’s climate history when changes in Earth’s orbit strengthened the African monsoon and transformed much of the Sahara into a greener, wetter world. But it did not last. As the climate system changed, rainfall weakened, lakes retreated, vegetation disappeared, and the Green Sahara gradually gave way to the desert we know today. In this documentary, we follow the evidence left behind in ancient lake beds, sediments, fossils, rock art, and landscapes to understand how the Sahara changed so dramatically — and what ultimately brought the green world to an end. This is the story of a lost Sahara. A world of water, grasslands, animals, and people — buried beneath one of the most extreme deserts on Earth. Subscribe to The Unwritten Earth for cinematic documentaries about Earth’s forgotten worlds, ancient climates, lost oceans, geological mysteries, and the forces that shaped our planet.