Green Sahara

In an alternate timeline where the subtle gravitational forces of other celestial bodies did not change as they did here, the African Humid Period never ended, with drastic consequences for the world. What is, in our timeline, known as the Sahara Desert is instead a fertile land of savanna, wetland and forest, pockmarked with great lakes and rivers. Where a harsh wasteland is for us, megafauna roam amidst a rich ecosystem.   On the banks of rivers and the great freshwater seas, African empires have emerged, civilizations of advancement on the order of the Egyptians or Mayans, neither of which exist in this timeline. Meanwhile, in the open plains in between, nomadic hunter-gatherer tribes roam, with varying relationships with their more technological neighbours.