The period from 9000 to 6000 BC has left very little in the way of archaeological evidence. Around 6000 BC, Neolithic settlements appear all over Egypt. Studies based on morphological, genetic, and archaeological data have attributed these settlements to migrants from the Fertile Crescent in the Near East returning during the Egyptian and North African Neolithic, bringing agriculture to the region. Jared Diamond, in a non-scholarly work, proposes other regions in Africa independently developed agriculture at about the same time: the Ethiopian highlands, the Sahel, and West Africa.