Metal used by craftspeople in pre-Inca Peru may have travelled hundreds of kilometres from present-day Bolivia, revealing the extent of ancient trade and technological networks across the Andes, according to new archaeological research.
Scientists reached the conclusion after analysing metallurgical waste recovered from the burial of a young metalworker at Castillo de Huarmey, a major Wari archaeological site on Peru’s northern coast.
Chemical and isotopic evidence suggests the material most likely originated around Pulacayo in modern Bolivia before being transported across the Andes, possibly as partially processed metal or semi-finished products.
Clue Found in Ancient Metalworker’s Grave
Castillo de Huarmey was an important Wari necropolis more than 1,300 years ago. The Wari developed an extensive network of administrative and ceremonial centres and roads centuries before the rise of the Inca Empire.
In 2012, an international archaeological team led by Polish researchers discovered the first intact royal Wari tomb at the site. Subsequent excavations revealed the graves of specialised craftspeople.
One burial, described by researchers as a “metallurgist’s grave”, contained the remains of a man approximately 20 years old.
More than a dozen bronze objects were buried with him, including a metal saw, axe, knives and chisels. Researchers also discovered a small piece of dark material in his hand.
The object was identified as speiss or matte, a metallurgical by-product created during the smelting of metal ores.
Despite its unremarkable appearance, the fragment contained evidence that allowed researchers to investigate where the raw material originated.
Geological ‘Fingerprint’ Points to Bolivia
Researchers from institutions including the University of Warsaw, University of Silesia, Polish Academy of Sciences, University of Florida and Juniata College subjected the fragment to lead isotope analysis.
Different ore deposits contain distinctive proportions of naturally occurring lead isotopes, effectively providing researchers with a geological fingerprint that can be compared with known deposits.
Scientists compared the Castillo de Huarmey sample with data from ores, rocks and metal artefacts across Peru, Bolivia, Chile, Argentina and other parts of the Andes.
Several potential sources initially emerged, including deposits in southern Peru and Bolivia. However, when isotope results were combined with chemical and mineralogical evidence, researchers identified the Pulacayo region of Bolivia as the most likely source.
Previous analysis of other metal objects from Castillo de Huarmey has also pointed towards the same region.
Pulacayo later became one of South America’s most important mining areas, particularly for silver, although copper was also extracted there during pre-Inca periods.
Metal May Have Travelled by Llama Caravan
Rather than transporting large quantities of heavy ore containing relatively small amounts of usable metal, researchers believe ancient communities probably processed the material near the mines before sending it north.
Metal could therefore have arrived at Castillo de Huarmey as partially processed material, semi-finished products or even completed objects intended to be melted down and reused.
The material may have travelled through the Andes in llama caravans, while researchers suggest some shipments could also have been transported along maritime routes.
Such long-distance movement raises the possibility that technological expertise travelled alongside the metal. Specialist craftspeople and knowledge of sophisticated metallurgical techniques may have circulated through the same networks.
The fragment placed in the young metalworker’s hand could have been produced during metalworking at Castillo de Huarmey and may have served as a technological reference sample, a quality benchmark or a symbol of the deceased man’s profession and status.
However, archaeologists have yet to discover smelting furnaces or large concentrations of metallurgical waste at the site, meaning there is currently no definitive evidence that primary smelting took place there.
The findings nevertheless provide further evidence of extensive economic and technological connections spanning the Andes centuries before the Inca Empire emerged.
Header Image Credit : M.Giersz
Sources : PAP