The Kalahari Desert is a large semi-arid sandy savannah in Southern Africa extending 900,000 square kilometres (350,000 sq mi), covering much of Botswana and parts of Namibia and South Africa, as semi-desert, with huge tracts of excellent grazing after good rains. The Kalahari supports more animals and plants than a true desert. There are small amounts of rainfall and the summer temperature is very high. It usually receives 3-7.5 inches (76-190 mm) of rain per year. The surrounding Kalahari Basin covers over 2,500,000 square kilometres (970,000 sq mi) extending farther into Botswana, Namibia and South Africa, and encroaching into parts of Angola, Zambia and Zimbabwe. The only permanent river, the Okavango, flows into a delta in the northwest, forming marshes that are rich in wildlife. Ancient dry riverbeds-called omuramba-traverse the Central Northern reaches of the Kalahari and provide standing pools of water during the rainy season. Previously havens for wild animals from elephant to giraffe, and for predators such as lion and cheetah, the riverbeds are now mostly grazing spots, though leopard or cheetah can still be found.
The Kalahari has vast areas covered by red sand without any permanent surface water. Drainage is by dry valleys, seasonally inundated pans, and the large salt pans of the Makgadikgadi Pan in Botswana and Etosha Pan in Namibia. However, the Kalahari is not a true desert. Parts of the Kalahari receive over 250 millimetres (9.8 in) of erratic rainfall annually and are quite well vegetated; it is only truly arid in the southwest with under 175 millimetres (6.9 in) of rain annually, making the Kalahari a fossil desert.The Bushmen have lived in the Kalahari for 20,000 years as hunter-gatherers. They hunt wild game with bows and arrows and gather edible plants, such as berries, melons and nuts, as well as insects. Bushmen rarely drink water; they get most of their water requirements from plant roots and desert melons found on or under the desert floor. They often store water in the blown-out shells of ostrich eggs. The San languages are notable for a number of distinctive features, including click consonants.