Original: The surrounding Kalahari Basin covers over 2.5 million km² extending farther into Botswana, Namibia and South Africa, and encroaching into parts of Angola, Zambia and Zimbabwe.
Simplified: The surrounding Kalahari Basin covers over 2.5 million km² extending further into Botswana, Namibia and South Africa, and encroaching into parts of Angola, Zambia and Zimbabwe.