The Benin Bronzes, a group of sculptures and plaques created between the 16th and 19th centuries in the Kingdom of Benin (part of modern-day Nigeria), are perhaps best known for the ongoing discussions surrounding the repatriation of many of these artefacts, which were seized during the Benin Expedition of 1897 and are currently found in museums around Europe and the United States. However, the latest news regarding the famous artworks concerns a recent study exploring the origins of the material used to create them.
Despite their name, most of the Benin ‘Bronzes’ are in fact made of brass, widely accepted to have been imported from Europe in the form of manillas: horseshoe-shaped brass rings used as currency in transatlantic trade between the 16th and 19th centuries. Hundreds of millions of manillas were produced in Europe and dispatched to West Africa in this period – beginning from the start of the region’s trade with the Portuguese in the late 15th century – to be exchanged for goods like gold and ivory, as well as enslaved people. The idea that these manillas served as a key source of brass for the Benin Bronzes has been popularly believed for some time, but the two had never been linked conclusively, and the precise geographical origins of the Bronzes’ raw materials remained a mystery.
Hundreds of geochemical analyses of the Benin Bronzes have been carried out in the past, looking at the composition of the metals used to create them. Brass, an alloy of copper and zinc, often includes small amounts of other elements like lead, as well as impurities such as antimony, nickel, arsenic, and iron, and the proportions in which these elements occur can be used to determine whence the brass originated. Existing analyses of the Benin Bronzes have revealed, among other things, surprisingly uniform lead-isotope ratios across the objects examined. This is unexpected, given the number of different nations known to have traded brass with Africa during this period, and suggests that the material used to create the artworks came largely from a single source.
The new study, carried out by a team of international researchers, drew on these earlier analyses, comparing the known chemical compositions of the Benin artworks to those of 67 manillas – originating from five shipwrecks, in the United Kingdom, Spain, Ghana, and the United States, and three terrestrial sites, in Sweden, Ghana, and Sierra Leone – and to different ores around Europe to determine where the brass was most likely to have been produced.
The results revealed that the manillas with the closest compositions to the Benin Bronzes were those produced before the 18th century, specifically an early Portuguese type known as tacoais manillas. They also found that these early manillas are a close isotopic match for lead-zinc ores in Germany’s Rhineland, which historical records indicate was a well-established centre of brass industry from the 15th century onwards, responsible for producing large quantities of manillas for the Portuguese, Dutch, and other nations who traded with Africa.
These findings therefore suggest that the homogeneity observed in the lead isotopes of the Benin Bronzes is a reflection of the mass-export of brass manillas made in the German Rhineland area and their widespread use in West African metalworking between the 15th and 18th centuries. We know from documentary sources that the African traders for whom these manillas were produced were selective in the products they would accept. It is likely that the skilled craftspeople who made the Benin Bronzes were aware that the Rhenish tacoais manillas had the best composition for casting and therefore expressed a preference for these products. While we cannot say for certain that the tacoais manillas made in the German Rhineland were the only source of brass used in the production of Benin Bronzes, they were without a doubt the most significant.
These findings, which have been published in the journal PLOS ONE (https://doi.org/10.1371/journal.pone.0283415), answer a long-standing question about the origin of the brass used to create the spectacular works of art produced by the Kingdom of Benin, and also represent a significant contribution to the study of early Atlantic trade, African metalwork, and the consumption and production of metal goods in this period.
Text: Amy Brunskill / Images: Brandon Clifford, Whydah Pirate Museum, Yarmouth Massachussets; Tobias Skowronek; Metropolitan Museum of Art, New York, Michael C. Rockefeller Memorial Collection, gift of Nelson A Rockefeller, 1972