Isotopic and chemical evidence for long-distance trade of copper and tin into east-central Botswana, c. cal. AD 800–1650

The sites of Bosutswe, Khubu la Dintša and Lose in east-central Botswana provide evidence of the presence of an élite (marked by the use of Lose pottery) among commoners (marked by other pottery traditions). Prior work by Denbow and Miller (2007) noted evidence of bronze at Bosutswe. This paper extends their work by inferring the provenance of copper and tin at these three sites, using chemistry, lead isotopes and tin isotopes. Copper came from a remarkably wide range of sources; tin came from only one source but was combined with copper from several sources to make bronze. Bronze first appeared at Bosutswe in the thirteenth century AD, as early as at Mapungubwe, a major political centre further south in northern South Africa.