A great chunk in the middle of Botswana is occupied by the Central Kalahari Game Reserve. Indeed, at over 50,000km2, it is quite a whopping area. Comprised of grassland, scrubby bush and ancient dry riverbeds this doesn't really look like your quintessential desert landscape. However, since there is no surface water here, it is indeed a desert, and the flora and fauna are specially adapted to this harsh environment. You can expect to see giraffe, zebra, gemsbok, the famous black-maned lions, meerkats and rhino in certain areas. There is also a reasonable chance of seeing wild dog and cheetah if you are lucky.
Surprisingly, this is also home, sweet home to a diminishing group of people - the Bushmen. Although their way of life is increasingly affected by encroaching "civilisation", there are still groups that retain a hunter-gatherer existences, moving according to availability of food and shelter.
The Kalahari is a hostile and relatively inaccessible place. Most camps and lodges are located on the peripheries and there is not much opportunity to penetrate the interior. Strict regulations exist to save you from making the fatal error of exploring without adequate supplies and preparations. It is possible to explore the reserve on a mobile safari, but if you are just visiting for a few days, you will inevitably stay in one of the few small camps on the edge.