A second farming expansion filled the Ubangi basin and left no famous name

The Bantu expansion is the best known population movement in African history. A second one ran alongside it and is barely mentioned. Between about 3000 and 1000 BCE, peoples speaking Ubangian languages, a subgroup of the North Voltaic branch of Niger-Congo, spread through the lands immediately north of the Bantu regions. They settled most of the vast basin of the Ubangi River, which today means the Central African Republic and the far north of the Democratic Republic of Congo, and by the first millennium BCE their easternmost communities had crossed into western South Sudan. They farmed a mixture of African crops, with yams dominant in the wetter southern parts of the basin and sorghum in the drier north. Two branches of one language family, moving in the same millennia, each carrying agriculture into new country. The Bantu expansion has several hundred studies behind it. The Ubangian expansion, equally consequential for central Africa, has almost none. The imbalance is itself a finding.

Around 1500 BCE a distinct ceramic tradition, which archaeologists call the Barrancoid series, developed in the middle and lower stretches of the Orinoco valley in what is now Venezuela. Over time its makers moved downriver toward the coast. The people already holding that ground, the communities Rouse files under the Saladero heading, were pushed out of their positions along the river, and out of that disturbance came the subseries he named Cedrosan Saladoid. This is upstream bookkeeping that matters a great deal for Haiti. The Cedrosan Saladoid are the people who a thousand years later carried farming, pottery and village life out of South America and into the Antilles, island by island, until they reached Hispaniola. The population Columbus met in 1492 descended from them. So the chain that ends in the Taino villages of the north coast begins with a pottery style shifting position on a South American river three thousand years earlier.

Where social and economic stratification rose in several parts of Africa, it did not carry female subordination with it. The list is long. The authority of the Kandake at Meroe. Economically independent women running major commerce in West Africa down to recent centuries. Queen mothers holding power in West and Central African kingdoms, alongside other institutions through which women acted on the state. Women holding chiefships in the kingdoms of the southern savanna belt. And in Matamba a queen who was the customary monarch. In the matrilineal savanna societies a suitor needed the consent of the bride's mother and her sisters, worked bride service under their direction for months or years, and deferred to his mother in law for the rest of her life. Those customs turn up in societies whose Bantu languages sit on different deep branches, which puts them in place by the proto-Savanna Bantu period of the early second millennium BCE. Patriarchy is not the entry fee for complex society.

Crops domesticated in West Africa had taken root in southern Arabia by 3000 BCE. Once they were established in Yemen and Oman they went aboard ship, and before the third millennium was out they were growing on the Indian subcontinent. The archaeologist Dorian Fuller and his colleagues assembled the evidence: a sphere of intercontinental contact more than four thousand years old, running from Africa through southern Arabia into South Asia. The usual account of ancient long-distance trade opens with Mesopotamia and the Indus valley and gives Africa a line in the notes. Fuller's material puts African plant breeding at the head of the chain, with West African crops travelling thousands of kilometres through Arabian hands and changing what Indian farmers grew. Ehret's own summary is that historians have nearly everything still to learn here. A whole sphere of ancient exchange sat unexamined because the discipline had already settled that Africa contributed nothing to the connected world.