Istwa Nou

The rivers of the Congo basin carried more than iron. Sheep spread out of the African Great Lakes along the same routes, apparently starting in the first millennium BCE, and the vocabulary records the journey. One line of spread is marked by the word *-meme, which began among Central Sudanic speakers in the far southeast of what is now South Sudan and passed from language to language westward through the Bantu communities along the middle Congo, reaching the Atlantic coast at the river's mouth. A second line shows up in a Great Lakes Bantu word, *-panga, which travelled southwest in the same period from the early Bantu settlers of the lakes to the societies around and below the upper and middle Sankuru. Two words, two roads, two streams of animals. Each is documented independently through historical linguistics, and both follow the same river system that was carrying iron, goods and commercial obligation at the same time. The equatorial forest functioned as a corridor.

In the first centuries CE African smiths circulated a new body of forging technique, spreading it along the rivers of the Congo basin. Jan Vansina called the result Africa's second iron age. One product shows what the technique could do. The flange welded double bell was made by forging four flat sheets of iron, reheating each one, hammering it over a rounded form until it curved into a half bell with a flat flange standing out all round the curve, then welding the flanges of each pair together in the fire, then forging a curved iron handle and welding that to the tops of both bells so the instrument held as one piece. Every stage demands temperature control, symmetry and a sound weld. Smiths in the equatorial rainforest were still producing these bells in the nineteenth century, eighteen hundred years after the method appeared, which says the knowledge was taught, held and handed down without interruption across that whole span.