1–500 CE: (The Second Iron Age of Africa — New Developments in Iron-Forging Technology Spreading Along the River Routes of the Congo Basin in the Early First…

1–500 CE: (The Second Iron Age of Africa — New Developments in Iron-Forging Technology Spreading Along the River Routes of the Congo Basin in the Early First Millennium CE, Jan Vansina’s Designation of These Advances, and the Flange-Welded Double Bell as a Notable Product Requiring the Smith to Forge Four Flat Iron Sheets Then Hammer, Curve, and Weld Them into a Complex Two-Bell Instrument with a Curved Iron Handle, a Technological Tradition Still Alive in the Nineteenth Century): In the early first millennium CE, African smiths spread the knowledge of a notable new set of developments in iron-forging technology, with the new techniques again tending especially to disperse along the river routes of the Congo basin. Jan Vansina has called these developments the “second” iron age of Africa. One notable product that came out of these technological advances was the flange-welded double bell. The manufacturing process was extraordinarily demanding: the smith had first to forge four flat iron sheets, then reheat them to high temperature and hammer each, placed upon a rounded form, into a curved half-bell shape with a flat flange extending out all around the curved central portion. Next, the flanges of the two halves of each bell were welded together in the forge fire. Finally, a curved iron handle was forged and welded onto the top of both bells, attaching them to each other. This was not primitive hammering. This was precision metallurgy requiring mastery of sheet forging, controlled heating, symmetrical shaping, and flange welding — a sequence of operations that would challenge any smith in any era. That this technological tradition was still very much alive as late as the nineteenth century CE, when examples were being produced in the northwestern equatorial rainforest, testifies to the durability and sophistication of the knowledge systems that African smiths maintained across nearly two millennia.