Neolithic Subpluvial, or Holocene climatic optimum, or Holocene Wet Phase
7000 BCE
to 6901 BCE
The Neolithic Subpluvial, an extended period of wet and rainy conditions in the climate history of northern Africa, begins in the 7th millennium BCE and is strong for about 2000 years; it wanes over time and ends in the 4th millennium BCE.
Then the drier conditions that had prevailed prior to the Neolithic Subpluvial return; desertification advances, and the Sahara desert forms(or re-formed).
Arid conditions continue through to the present day.
Large areas of North, Central, and East Africa have hydrographic profiles significantly different from later norms.
Existing lakes have surfaces tens of meters higher than today, sometimes with alternative drainages: Lake Turkana, in present-day Kenya, drains into the Nile River basin.
Lake Chad reaches a maximum extent of some 400,000 square kilometers in surface area, larger than the modern Caspian Sea, with a surface level about 30 meters (100 feet) higher than its twentieth-century average.
Some shallower lakes and river systems exist in the subpluvial era that later disappear entirely, and are detectable today only via radar and satellite imagery.North Africa enjoys a fertile climate during the Neolithic Subpluvial; what is now the Sahara supports a savanna type of ecosystem, with elephant, giraffe, and other grassland and woodland animals now typical of the Sahel region south of the desert.
Clement and fertile conditions support human settlement of the Nile Valley in Egypt, as well as Neolithic societies in Sudan and throughout the region.
The culture that creates the rock art of Tassili n'Ajjer in southeastern Algeria flourishes during the subpluvial period.
