🔥 A metallurgy workshop over 2,400 years old

Despite decades of archaeological research, the beginnings of iron metallurgy in sub-Saharan Africa remain largely poorly understood.

This technological revolution, essential for producing efficient tools, appeared there at least 3,000 years ago. While exploring an archaeological site in eastern Senegal, an international team led by the University of Geneva (UNIGE) uncovered the remarkably well-preserved remains of an iron smelting workshop dating from the 4th century BC and used for nearly eight centuries.


This discovery, published in African Archaeological Review, provides valuable information to better understand metallurgical practices from the late prehistoric period in Africa.

In Europe, the Iron Age is generally placed between 800 BC and the end of the 1st century AD. But these chronological boundaries vary by region around the world. The earliest iron production would thus date back to the 2nd millennium BC in the regions of Anatolia, present-day Turkey, and the Caucasus. These techniques spread from there to Europe, but were they invented independently in Africa? The question remains open.

This site offers a unique opportunity to study the continuity and adaptation of an iron smelting technique over the long term.

Excavations led by a team coordinated by UNIGE, in partnership with the Institut Fondamental d'Afrique Noire (IFAN) in Dakar, shed new light on the origins of iron metallurgy in West Africa. At the Didé West 1 (DDW1) site, near the Falémé River valley in eastern Senegal, archaeologists discovered in 2018 an exceptionally well-preserved iron smelting workshop, used from the 4th century BC to the 4th century AD. Its longevity is remarkable as this type of site is usually only exploited for a few generations.

Well-preserved tuyeres and furnaces

The workshop consists of a vast mound of around a hundred tons of slag, an arrangement in arcs of about thirty used "tuyeres" - clay conduits that allowed air to be blown into the fire - and 35 circular furnace bases about 30 cm (about 12 inches) deep. This production of iron and steel was probably carried out on a small scale to meet local needs, particularly for making agricultural tools.

"Due to its exceptional quality of preservation, its age and duration of use, as well as its technical specificities, this site is remarkable. It offers a unique opportunity to study the continuity and adaptation of an iron smelting technique over the long term," says Mélissa Morel, postdoctoral researcher at the Laboratory of African Archaeology and Anthropology (ARCAN) in the Biology Section of the UNIGE Faculty of Sciences, and first author of the article.

Documenting practices

Since 2012, the team has been studying the current and past techniques of potters and blacksmiths in the Falémé Valley. They have identified several ancient traditions of iron ore smelting. At the DDW1 site, the spatial organization, the type of furnaces, and the waste found allow for the identification of the so-called FAL02 tradition. It is characterized by small circular furnaces, topped by a removable chimney, as well as large clay tuyeres.

A remarkable feature: these tuyeres do not have a single air outlet, but several small openings connected to the main conduit by perpendicular lateral channels, allowing air to be diffused towards the bottom of the furnace as well. Another unprecedented characteristic, the metallurgists used palm nuts as packing material for the bottom of the furnace, a practice previously unknown.

"Despite the very long period of use of this workshop, this tradition remained remarkably stable, undergoing only minor technical adjustments. This continuity contrasts with other African metallurgical contexts and highlights the importance of understanding the technical and cultural choices of the first metallurgists to produce iron," explains Anne Mayor, director of the ARCAN laboratory in the Biology Section of the UNIGE Faculty of Sciences and senior lecturer at the Global Studies Institute, who led this work.

The team's research continues on other sites in Senegal to compare practices and better understand the evolution of iron metallurgy skills. Today, only about a dozen well-documented and well-dated sites from the first millennium BC are known for the whole of West Africa.