When the Sahara Was Green

Thousands of rock paintings and engravings survive on the Tassili n’Ajjer plateau in modern Algeria. They depict people and animals, including water-dependent hippopotamuses and other species that have disappeared from the region. The oldest Saharan artistic traditions go back thousands of years before the Egyptian pyramids, though dating individual images is difficult. Together with geological and archaeological evidence, this art shows that the region once had wetter landscapes with savannas, water bodies, and river valleys; climate and vegetation changed gradually and unevenly from place to place.