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Photograph taken during the discovery of a pile of used tuyères, featuring intriguing transverse perforations, for photogrammetry purposes.
Photo Credit: © Anne Mayor
Scientific Frontline: Extended "At a Glance" Summary: Prehistoric West African Iron Metallurgy
The Core Concept: An exceptionally well-preserved iron-smelting workshop located in eastern Senegal provides detailed evidence of sub-Saharan African iron production dating back 2,400 years.
Key Distinction/Mechanism: Unlike typical metallurgical sites that are abandoned after a few generations, this workshop remained operational and remarkably stable for nearly eight centuries. The site operated using a specialized technique where large clay "tuyères" (air pipes) featured multiple perpendicular side ducts rather than a single outlet, allowing for highly optimized air distribution to the bottom of the furnace.
Major Frameworks/Components:
- FAL02 Metallurgical Tradition: A distinct iron-ore smelting practice utilizing small circular bloomery furnaces (approximately 30 cm deep) topped with removable chimneys.
- Advanced Tuyère System: Semicircular arrangements of engineered clay pipes designed with complex side openings to channel and distribute air efficiently during the smelting process.
- Novel Packing Materials: The previously undocumented use of palm nut seeds as foundational packing material at the base of the smelting furnaces.
Branch of Science: Archaeology, Archaeometallurgy, Anthropology.
Future Application: The findings provide comparative baseline data to refine historical models of human technological evolution and cultural adaptation, assisting future global excavations in identifying similar independent technological developments and ancient industrial continuities.
Why It Matters: The site challenges previous chronological frameworks regarding the origins, diffusion, and lifespan of early iron metallurgy. It offers a rare opportunity to study the long-term technical continuity and localized cultural choices of early African metallurgists who produced the efficient agricultural tools that drove regional development.
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| Aerial view of the Didé Ouest 1 iron reduction site following the 2018 excavation, showing an unusual deposit of used tuyères arranged in two semicircles. Photo Credit: © Camille Ollier |
The discovery of a 2,400-year-old metalworking workshop in Senegal provides new insights into the history of iron production in Africa.
Despite decades of archaeological research, the origins of iron metallurgy in sub-Saharan Africa remain largely unclear. Yet this technological revolution—crucial for producing efficient agricultural tools—emerged there at least 3,000 years ago. While investigating an archaeological site in eastern Senegal, an international team led by the University of Geneva (UNIGE) uncovered exceptionally well-preserved remains of an ironworking workshop dating back to the 4th century BCE and used for nearly eight centuries. The discovery, published in African Archaeological Review, provides new insights into late prehistoric metallurgical practices in Africa.
In Europe, the Iron Age is generally dated from around 800 BCE to the end of the 1st century CE. However, these chronological frameworks vary widely across different regions of the world. The earliest evidence for iron production is thought to date to the 2nd millennium BCE in Anatolia—modern-day Turkey—and the Caucasus. This technique spread from there to Europe, but did it develop independently in Africa? The question remains open.
This site offers a rare opportunity to study the continuity and adaptation of an iron smelting technique over the long term.
Excavations carried out by a team coordinated by UNIGE, in partnership with the Institut Fondamental d’Afrique Noire (IFAN) in Dakar, shed new light new light on the emergence of iron metallurgy in West Africa. At the site of Didé West 1 (DDW1), near the Falémé River valley in eastern Senegal, archaeologists uncovered an exceptionally well-preserved iron-smelting workshop in 2018 that was in use from the 4th century BCE to the 4th century CE. Its longevity is particularly striking, as such sites are typically used for only a few generations.
Well-preserved “tuyères” and bloomery furnaces
The workshop consists of a large heap containing around a hundred tons of slag, a semicircular arrangement of about thirty used “tuyères”—clay pipes that channel air into the furnace—and 35 circular furnace bases, each approximately 30 cm deep. This iron and steel production was likely carried out on a small scale to meet local needs, particularly for the manufacture of agricultural tools.
“Thanks to its exceptional state of preservation, its age, the length of time it remained in use, and its distinctive technical features, this site is truly unique. It offers a rare 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 Archaeology of Africa & Anthropology (ARCAN) within the Biology Section of the Faculty of Science at UNIGE, and lead author of the article.
Documenting practices
Since 2012, the team has been studying both past and present techniques used by potters and blacksmiths in the Falémé Valley. The work of its members has identified several distinct ancient traditions of iron‑ore smelting. At DDW1, the spatial organization, furnace morphology and associated waste products point to the tradition known as FAL02. It is characterized by small circular furnaces topped with a removable chimney, as well as large clay “tuyères”. A key feature is that these “tuyères” do not have a single air outlet, but multiple small openings are connected to the main channel by perpendicular side ducts. This design allows air to be distributed to the bottom of the furnace. Another distinctive characteristic is the use of palm nut seeds as packing material at the base of the furnace—a practice not previously documented.
“Despite the very long period during which this workshop operated, 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 made by early metallurgists in iron production,” explains Anne Mayor, director of the ARCAN laboratory in the Biology Section of the Faculty of Science at UNIGE and senior lecturer and researcher at the Global Studies Institute, who led the project.
The team’s research is continuing at other sites in Senegal to compare smelting practices and gain a better understanding of how ironworking techniques developed and spread. To date, only around a dozen sites dating to the first millennium of BCE have been well documented and reliably dated across West Africa.
Published in journal: African Archaeological Review
Authors: Mélissa Morel, Pierre Lamotte, Ladji Dianifaba, Alexander Walmsley, Irka Hajdas, Vincent Serneels, and Anne Mayor
Source/Credit: Université de Genève
Reference Number: arch033126_01