IRON
Across Bénin, as in West Africa as a whole, very many remains of ancient production of iron have been found, going back to the first millennium BC. The whole production can be followed or is implied from archaeological finds: Extraction of iron ore, roasting of the ore, building of funnel-like clay ovens, burning of charcoal, provision of water, stoking of ovens, freeing of bloom from the oven, discarding of slag, cleaning of the bloom, and making of iron bars and tools.
For instance, near Dogbo, to the south of Abomey, mines for extraction of ore are recorded. These consist of a maze of narrow corridors a couple of metres below surface. The entrances to the mines are slooping (unlike those of the caves). There are smaller holes for air intake. Near Abomey open mines have been found, still carrying scars from hoes.
Standing iron ovens have not been found in southern Bénin, but do occur in the North, where ancient methods iron production lived on till about 100 years ago. In the South fragments of oven occur in the heaps of slag discarded behind the ovens when the bloom was recovered. The ovens were tall and funnel-shaped and used blow-pipes (tuyères) for air-intake.
The slag heaps or even mounds are also dating the production and give indications of its size. Interestingly, all the slag heaps in southern Bénin are most likely older than the Dahomean kingdom. The earliest dates - so far - are of around 800 AD. The ancient iron production was very large indeed. At Dogbo there is hundreds of slag heaps from around 1500 AD, the largest being 100x45x12.5m, holding at least 58,500 ton slag. This amount of slag equals a yield of at 2600 ton iron, or a minimum of 2,363,000 axe-heads or “coupe-coupes” (machetes).Most slag heaps are much smaller. On a single locality one may, for instance, find eight medium-sized slag heaps, each with a height of a couple of metres. Such production still equals 300 ton iron, including a use of 7,000 ton of charcoal.The environmental effects were probably so great that they explain the cessation of the production. What is more, we have no knowledge of the culture that produced the iron. Perhaps a link can be established with nearby Tado in eastern Togo, or with an Allada before Kingdom of Allada. Otherwise, we may have to look to Nigeria and its early cities.
A production of this size, even over several hundred years, seems to exceed local demands. A possible export to the Islamic north is therefore a suggestion, along with the gold, ivory and slaves of West Africa, at least from around 1000 AD. With the arrival of the Europeans, imported bar-iron was preferred.