For a long time it was unclear where the metal for the famous Benin bronzes came from. An analysis now reveals that the African works of art were made of German brass. The metal was produced in the Rhineland up to the 18th century and cast into so-called manillae - horseshoe-shaped brass rings. These were exported to Africa, where they were used as "currency" by slave traders and used as raw material for the famous Benin bronzes in the Kingdom of Benin in modern-day Nigeria.
The Benin Bronzes are world-renowned brass sculptures and reliefs made in the Kingdom of Benin, in present-day Nigeria. Thousands of these works of art were looted during the colonial period and especially in the 19th century and brought to Europe and the USA. German collectors and museums also acquired numerous Benin bronzes. They were only officially returned to Nigerian ownership in July 2022, but remain largely on loan in Germany.
“Slave money” as raw material?
But despite the great prominence of the Benin bronzes, it was previously unclear where the metallic raw material for the works of art, mostly made of brass, came from. “The Benin bronzes are the most famous ancient works of art in all of West Africa. Where the enormous amounts of metal came from and how Benin got its brass was a mystery for a long time," says lead author Tobias Skowronek from the Georg Agricola Technical University in Bochum. However, it has been suggested that manillas, horseshoe-shaped hoops made of copper or brass, were used in its manufacture.
The manillas served European traders and slave hunters in Africa as a means of payment and were therefore also referred to as "slave money". "Hundreds of thousands of these manillas were shipped from Europe to Africa at the beginning of the Portuguese African trade in the late 15th century," explain Skowronek and his colleagues. So it made sense that these rings would be melted down and then used as the raw material for the Benin bronzes. However, this has not yet been proven, partly because comparative chemical analyzes have yielded contradictory results.
Bronzes are made of German brass
In order to clarify the question of the raw material for the Benin bronzes, Skowronek and his team again analyzed 67 manillas that came from five shipwrecks in the Atlantic and three localities on land. The ships and finds associated with the African trade date from the 16th to the 19th centuries. The focus of the analyzes was on the lead isotope proportions, because these are specific depending on the metal ore and origin, like a kind of chemical fingerprint. It turned out that many of the manillas produced up to the 18th century contained similar proportions of lead isotopes as the Benin bronzes. Skowronek and his colleagues conclude that these manillas must have been the main raw material for the bronzes.
However, the analyzes revealed something even more surprising: the lead isotopes in the brass of the manillas matched amazingly well with ores and brass from the Rhineland. “We are thus proving something completely unexpected: the brass of the masterly Benin works of art did not come from Great Britain or Flanders, as was long assumed, but from western Germany,” says Skowronek. "This is the first time that this connection has been scientifically proven."
It is now clear that the metal for the Benin bronzes came mostly from Germany. In the early modern period, the Rhineland was a center of metal processing and brass production. Up until the 18th century, the Rhenish metalworks were also a main supplier of the manillas exported to Africa. The current results not only clarify the question of the raw material for the Benin bronzes, they are also of great social relevance. Because they provide further information about Germany's role in the international slave trade: A large part of the early "slave money" came from our country.
Source: Technical University Georg Agricola; Specialist article: PLoS ONE, doi: 10.1371/journal.pone.0283415