In the 19th century, Christian Jurgensen Thomsen, the curator of the Danish National Museum, began to classify cutting tools according to the material used to make them: stone, bronze, and iron. He then extended this classification to other materials which were found with them. This gave rise to a chronological scheme, known as the Three-Age System: Stone Age, Bronze Age, and Iron Age. Today, the Three-Age system provides a basic set of chronological markers which are widely used in European prehistory. The system is not seen as an inevitable progression of cultural and technological development, but simply a way of providing relative dating classification.
Unlike Europe, Sub-Saharan Africa lacks a Bronze Age, a period in which softer metals, such as copper, were made into artifacts. In Sub-Saharan Africa there is a Stone Age and an Iron Age. The earliest evidence of iron-working in Africa south of the Sahara comes from the Jos Plateau in Nigeria and from the area around Lake Victoria. In both of these areas, early metallurgy shows little evidence of local antecedents. Therefore, many archaeologists have suggested that the knowledge of ironworking and smelting diffused from the north: perhaps from the Carthaginian colonies of western Mediterranean Africa or from the Nile Valley. However, there is little direct evidence supporting these long distance connections.
In Nigeria, the Nok culture appears about 1000 BCE in central Nigeria. By 500 BCE, smelting and forging iron for tools were well-developed. One of the features of this early farming and ironworking culture was the production of life-sized terracotta sculptures. Some archaeologists have suggested that these sculptures have magico-religious significance, either as field altars or in connection with iron smelting.
Examples of the terracotta figures are shown below:
At the Nok site of Taruga, people were engaged in iron-working by 600 BCE. The people farmed and raised cattle. Archaeologists have uncovered 13 iron smelting furnaces at Taruga. At this time, the climate was moister and more heavily wooded than it is today. As the climate became drier, the people migrated south and may have been the ancestors of the Igala, Nupe, Yoruba, and Ibo.
Shown below is a terracotta figure from Taruga:
At the Nok site of Samun Dukiya (300 BCE to 100 BCE), there is no evidence of an earlier occupation. The iron artifacts found at this site include hooks, bracelets, knives, arrowheads, spearheads, and a cylinder made from a rolled metal band.
In southern Africa, farming and metallurgy seem to be associated with each other and appear about the same time. In territories which had been inhabited by stone-tool-using nomadic hunters-and-gatherers, there appear permanent villages of people who are cultivating crops and herding animals. They are also working with metal and making pottery. The pottery from these early villages has a common stylistic tradition which appears to be related to the early iron-workers in the Lake Victoria region. These changes are a marked contrast to the earlier cultures and thus many archaeologists view this as a migration of people into the area.
This migration, some people suggest, was the Bantu migration. The Bantu languages are a family of closely related languages which originated in the borderlands between Cameroon and Nigeria. This migration began about three thousand years ago. It was not a mass migration, but small numbers of migrants who spread out looking for grazing lands and lands suitable for cultivation. By the third century of the current era, these farming people had established villages alongside the earlier hunting-and-gathering people and had begun to absorb or replace them.
Both the archaeological and linguistic evidence suggest that the interaction between the newcomers and the existing peoples was prolonged. The archaeology in the region for this early time period has focused on technology and domestic economy. We know relatively little about the political systems or religion.