Between 9,000 and 6,000 years ago, the Sahara desert experienced wet and rainy conditions, supporting abundant life. Rivers and lakes formed due to the climate changes, allowing vegetation to thrive and supporting populations of animals like crocodiles, elephants, and fish. Human civilizations developed during this "Green Sahara" period, using the rivers for transportation and developing skills like cooking, pottery-making, and cave painting. Then around 6,000 years ago, the climate shifted back to arid conditions, and the desert that exists today re-formed in the Sahara region of northern Africa.