Long distance trade of copper ingots from the eastern Copperbelt (Democratic Republic of Congo) to central Malawi

In 1967 a hoard of eight X-shaped copper ingots was discovered in the village of Chombe, in central Malawi. These are all of the HXR ingot type, of which several hundred examples have been found in Zambia and Zimbabwe. They are thought to have been manufactured between the 14th and late 18th centuries CE. In 2024 we sampled five of the Chombe ingots to analyze for lead isotope analysis (LIA) and bulk ICP-MS chemical analysis at the University of Missouri Research Reactor (MURR). We conclude that all five ingots derive from the Kipushi ore body, located near Lubumbashi in the Democratic Republic of Congo (DRC). The straight-line distance between ore source and find spot is about 790 km, but we suggest that the ingots may have travelled a longer but easier route by canoe down the Kafue and Zambezi rivers, with only the last 220+ km overland to central Malawi (ca. 1200 km total). These ingots are much thinner, and therefore lighter, than typical HXR ingots, and are the only HXR ingots known so far to have been sand-cast. We infer that at some point along their journey the original ingots were recast, and discuss why this might have been done.