Algeria. Rock painting, Tassili N'Ajjer Plateau. Tassili n'Ajjer (Plateau of the Rivers) is a mountain range in the Algerian section of the Sahara Desert. It is a vast plateau in south-east Algeria at the borders of Libya and Niger, covering an area of 45,000 miles. The range is also noted for its prehistoric rock art and other ancient archaeological sites, dating from Neolithic times when the local climate was more moist, with savannah rather than desert. The art depicts herds of cattle, large wild animals including crocodiles, and human activities such as hunting and dancing. 15,000 petroglyphs have been identified to date.