Bronze Age as the First World-System

In the 21^st century B.C. global trade finally took off. Global, insofar it extended from Scandinavia to the Indus, from the Urals to the Nile, quite possibly, via the steppe, all the way to the Yellow river. It was carried by human porters, the caravans of donkeys, and the newly invented keeled ships under sail. The trade in luxury cloth, wine, ivory, gem stones, but above all, in copper and tin: the metals undergirding the Bronze Age