Kings stop monopolising trade and start taxing it

East of the Mediterranean, in lands that had held states and steep social hierarchies for centuries, the new commerce changed who moved goods. Merchants took over from the agents of kings and priesthoods as the principal carriers of long-distance trade. Skilled artisans found buyers beyond the palace and the temple and worked for a wider market. Kings adjusted. They gave up monopolising the acquisition of valuable goods and took taxes on the traffic and tolls on the roads instead, raising the value of what they taxed by protecting the merchants and the routes. Protection sold for revenue is the origin of a great deal of later state finance. By the middle of the first millennium BCE the Garamantes of the central Sahara had joined West African trade to the Mediterranean system. Gold and other goods from the Sudan belt reached Carthage and later Rome through them, on routes the camel and Islam would inherit centuries afterwards.

Words for iron and for the work of the forge spread eastward across central Africa until they stopped in the west of South Sudan, along what is now the Ethiopian border. They stopped because another body of ironworking terms was coming the other way, southward out of the northern Ethiopian highlands. The two met in eastern South Sudan around the middle of the first millennium BCE. Each set carries its own words for the furnace, the smith and the tools, and each traces back to a different chain of transmission, one African in origin and one reaching the highlands from the Middle East across the Red Sea. Had iron been born once in Anatolia and radiated outward from there, the vocabulary across this whole region would descend from a single root. Instead there are two lexical systems running into each other from opposite directions, thousands of kilometres from where either began. That meeting place is where the single origin theory stops working.