Africa is the world’s second-largest and second-most-populous continent. At about 30.2 million km² (11.7 million sq mi) including adjacent islands, it covers six percent of the Earth’s total surface area and 20.4 percent of the total land area. With 1.0 billion people (as of 2009, see table), it accounts for about 15% of the world’s human population. The continent is surrounded by the Mediterranean Sea to the north, both the Suez Canal and the Red Sea along the Sinai Peninsula to the northeast, the Indian Ocean to the southeast, and the Atlantic Ocean to the west. The continent includes Madagascar and various archipelagoes. It has 54 fully recognized sovereign states (“countries”), 9 territories and two de facto independent states with limited or no recognition.
Africa, particularly central Eastern Africa, is widely accepted as the origin of humans and the Hominidae clade (great apes), as evidenced by the discovery of the earliest hominids and their ancestors, as well as later ones that have been dated to around seven million years ago – including Sahelanthropus tchadensis, Australopithecus africanus, A. afarensis, Homo erectus, H. habilis and H. ergaster – with the earliest Homo sapiens (modern human) found in Ethiopia being dated to circa 200,000 years ago. Africa straddles the equator and encompasses numerous climate areas; it is the only continent to stretch from the northern temperate to southern temperate zones.
Africa is considered by most paleoanthropologists to be the oldest inhabited territory on Earth, with the human species originating from the continent. During the middle of the 20th century, anthropologists discovered many fossils and evidence of human occupation perhaps as early as 7 million years ago. Fossil remains of several species of early apelike humans thought to have evolved into modern man, such as Australopithecus afarensis (radiometrically dated to approximately 3.9–3.0 million years BC), Paranthropus boisei (c. 2.3–1.4 million years BC) and Homo ergaster (c. 1.9 million–600,000 years BC) have been discovered.
Throughout humanity’s prehistory, Africa like all other continents had no nation states, and was instead inhabited by groups of hunter-gatherers such as the Khoi and San.
At the end of the Ice Ages, estimated to have been around 10,500 BC, the Sahara had again become a green fertile valley, and its African populations returned from the interior and coastal highlands in Sub-Saharan Africa. However, the warming and drying climate meant that by 5000 BC, the Sahara region was becoming increasingly dry and hostile. The population trekked out of the Sahara region towards the Nile Valley below the Second Cataract where they made permanent or semi-permanent settlements. A major climatic recession occurred, lessening the heavy and persistent rains in Central and Eastern Africa. Since this time, dry conditions have prevailed in Eastern Africa and, increasingly during the last 200 years, in Ethiopia.
The domestication of cattle in Africa preceded agriculture and seems to have exitted alongside hunter-gatherer cultures. It is speculated that by 6000 BC, cattle were already domesticated in North Africa. In the Sahara-Nile complex, people domesticated many animals, including the donkey and a small screw-horned goat which was common from Algeria to Nubia. In the year 4000 BC, the climate of the Sahara started to become drier at an exceedingly fast pace. This climate change caused lakes and rivers to shrink significantly and caused increasing desertification. This, in turn, decreased the amount of land conducive to settlements and helped to cause migrations of farming communities to the more tropical climate of West Africa.
By the first millennium BC, ironworking had been introduced in Northern Africa and quickly spread across the Sahara into the northern parts of sub-Saharan Africa, and by 500 BC, metalworking began to become commonplace in West Africa. Ironworking was fully established by roughly 500 BC in many areas of East and West Africa, although other regions didn’t begin ironworking until the early centuries AD. Copper objects from Egypt, North Africa, Nubia and Ethiopia dating from around 500 BC have been excavated in West Africa, suggesting that Trans-Saharan trade networks had been established by this date.