The Sahel is the transitional zone between the Sahara and the tropical savanna (the Sudan region) and forest-savanna mosaic to the south. The Horn of Africa and large areas of Sudan are geographically part of Sub-Saharan Africa, but also part of the Arab world.

The Sub-Saharan region is also known as Black Africa, in reference to its many black populations. Commentators in Arabic in the medieval period used a similar term, bilâd as-sûdân, for the region south of the Sahara, which literally translates as "land of the blacks."

According to scientific studies natural human skin colour diversity is highest in black or Sub-Saharan African populations.

Since probably the 5.9 kiloyear event, the Saharan and Sub-Saharan regions of Africa have been separated by the extremely harsh climate of the sparsely populated Sahara, forming an effective barrier interrupted by only the Nile River in Sudan, though the Nile was blocked by the river's cataracts. The Sahara Pump Theory explains how flora and fauna (including Homo sapiens) left Africa to penetrate the Middle East and beyond to Europe and Asia. African pluvial periods are associated with a "wet Sahara" phase during which larger lakes and more rivers exist.

Sub-Saharan Africa has a wide variety of climate zones or biomes. South Africa and the Democratic Republic of the Congo in particular are considered Megadiverse countries.

Nubia in present day Sudan and other regions south of Egypt, in Sub-Saharan Africa, was referred to as "Ethiopia" or "Aethiopia" ("land of the burnt face") by the Greeks.

According to paleontology, early hominid skull anatomy was similar to their close cousins, the great African forest apes, gorilla and chimpanzee but they had adopted a bipedal locomotion and freed hands, giving them a crucial advantage, as this enabled them to live in both forested areas and on the open savanna at a time when Africa was drying up, with savanna encroaching on forested areas. This occurred 10 million to 5 million years ago.

By 3 million years ago several australopithecine(southern apes) hominid species had developed throughout southern, eastern and central Africa. They were tool users not makers of tools. They scavenged for meat and were vegetarians.

About 2.3 million BC, the next major evolutionary step occurred approximately, when primitive stone tools were first used to scavenge kills made by other predators, and harvest carrion for their bones and marrow. In hunting, H. habilis was probably not capable of competing with large predators, and was still more prey than hunter, although H. habilis probably did steal eggs from nests, and may have been able to catch small game, and weakened larger prey (cubs and older animals). The tools were classed as Oldowan.

Around 1.8 million years ago Homo ergaster first appeared in the fossil record in Africa. From Homo ergaster, [Homo erectus](upright man) evolved 1.5 million years. Some of the earlier representatives of this species were still fairly small brained and used primitive stone tools, much like H. habilis. The brain later grew in size and H. erectus eventually developed a more complex stone tool technology called the Acheulean. Possibly the first hunters, H. erectus mastered the art of making fire, and were the first hominids to leave Africa, colonizing the entire Old World, and perhaps later giving rise to Homo floresiensis. Although some recent writers suggest that H. georgicus, a H. habilis descendant, was the first and most primitive hominid to ever live outside Africa, many scientists consider H. georgicus to be an early and primitive member of the H. erectus species.