Five sets of megalithic graves suggest five small states in the Sahara

The Aïr mountains sit at the southern edge of the Sahara in what is now Niger, twelve hundred kilometres east of the inland delta of the Niger. Between roughly 2500 and 1500 BCE the people living there worked out copper smelting, and once the industry was running Aïr became the supplier of copper across the central and western Sudan belt. Urban development in the massif itself may have come later. Something else came early. In five separate parts of Aïr, people began building megalithic burial sites. The archaeologist Augustin Holl proposes that these mark five small polities in the centuries between 1500 and 1000 BCE, each holding a share of the copper bearing ground. Monumental construction, political authority and control of a metal that everyone downstream needed, all present in the middle of the desert at a date when the standard narrative has nothing at all to say about the region. The routes running out from those mines became the arteries of West African trade.

Around 1000 BCE Ortoiroid communities completed a long movement up the Lesser Antilles and reached Puerto Rico. Their arrival brought them within reach of a different world. Hispaniola, immediately west across the Mona Passage, was held by Casimiroid peoples who had entered the islands from another direction entirely and had been there for thousands of years. The two now shared a frontier. Rouse reads the archaeology of the following centuries as a flow of technique running northwest to southeast, from the Casimiroid side into the Ortoiroid one, carrying ways of flaking and grinding stone. That direction is the interesting part. The newcomers coming up the chain were the ones learning. Whatever the older population of Hispaniola had worked out about local stone over several millennia of residence was worth adopting, and it moved across the passage into Puerto Rico. The Mona Passage has been a channel of exchange for three thousand years, and Haiti sits on the western side of it.

Two sites carry the earliest known evidence of iron smelting on earth. One is Ôboui, in the west of the Central African Republic. The second, Gbatoro, lies about a hundred kilometres away over the border in Cameroon. Radiocarbon puts both at 1800 BCE or earlier. The excavation reports describe careful work on undisturbed ground, with clean layers sealing the deposits above and below. At Ôboui the whole sequence of the craft is present in one workshop: furnace structures, the clay tuyeres that fed air to the fire, pieces of worked iron, slag, stone anvils for hammering, and charcoal in quantity for dating. Four thousand years ago, in the middle of Africa, people were smelting and forging iron. These are not stray dates from a thin dig. They are two sites, both inside the zone the linguistic evidence had already predicted, both fully excavated and both dated. African iron is older than Anatolian iron by at least three centuries.

Metallurgy is usually taught as a ladder. People start with copper, which melts at a low temperature and sometimes shows up as visible metal in rock, and only later work out that fiercer heat will pull iron out of ore. Across large parts of Africa the ladder has its rungs in a different order. In the earliest ironworking areas, in the Central African Republic and across most of the continent below the Sahara, iron was known and used before copper was. Prior copper smelting cannot be the explanation for the African discovery, because there was no prior copper smelting. Something else supplied the knowledge, and the likeliest candidate is ceramics. Women had been firing clay in high heat for thousands of years by then, and the control of temperature and airflow that pottery demands is most of what a smelting furnace needs. The African road to iron went through the kiln. The Bronze Age that world history courses treat as a universal stage never happened here.