The region west of the Falémé Valley in eastern Senegal, where several distinct smelting traditions have been identified, is key to understanding early West African iron metallurgy, which remains globally underdocumented in this part of the continent. Excavations carried out in 2018 and 2022 at the Didé West 1 site (DDW1) uncovered an exceptionally well-preserved slag heap dated between the 4th century BCE and the 4th century CE, representing nearly eight centuries of activity. The site belongs to the FAL02 smelting tradition and revealed 35 circular clay-lined furnace bases producing internal slag blocks, numerous massive multiperforated tuyeres, and the distinctive use of palm nuts as stuffing material. This outstanding preservation offers a unique opportunity to investigate long-term technological continuity and adaptation. The stratigraphic and spatial analyses made it possible to reconstruct both the chronological sequence and the evolution of the workshop’s layout, which gradually shifted northward over time. Quantitative estimations suggest that iron smelting was likely small-scale and seasonal, primarily aimed at meeting local needs. Despite its extraordinary longevity, the tradition remained remarkably stable, with only minor technical adjustments. This technique and its continuity contrast with other metallurgical contexts and highlight the significance of technological choices in early iron production.