Glass Beads Help to Map Unknown Medieval African Trade Routes

For several decades, a team of researchers have been carrying out excavations at old cemeteries and villages at sites in central Mali and eastern Senegal. Over the years they’ve come across a handful of glass beads dating from between the 7th and 13th centuries AD. The recent analysis of those beads reveals that Medieval African trade routes were more extensive than previously believed.

The new finding is the result of work by archaeologists from the University of Geneva (UNIGE) working in partnership with the Institut de Recherche sur les Archéomatériaux at the Centre Ernest-Babelon in Orléans, France. EurekAlert!reports that a team from the Archaeology and Population in Africa Laboratory of UNIGE discovered the beads at three rural sites in Mali and Senegal and the analysis of the beads has helped the researchers “to understand their provenance and form a picture of what trade was like at a time when the first African kingdoms were developing.”

The Ghana empire rose to power mainly by capitalizing from the gold trade, as well as copper, iron-smelting and salt. (HomeTeam History / YouTube)

How Did They Analyze the Medieval Glass Beads?

The archaeologists analyzed the morphological and technical characteristics alongside the chemical composition of the 16 medieval beads. Taken together, these features help to paint a clearer picture of the origins of the glass beads. That information was used by the researchers to map out medieval African trade routes between the places where the glass was produced and the sites where the beads were used.

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A University of Geneva press release explains that there are three main components which are needed to produce glass – silica from quartz ore or sand, mineral or vegetable flux to help melt the silica, and lime from limestone rocks or shells to stabilize the structure of the glass. Miriam Truffa Giachet, the first author of the study, states that “By analyzing the chemical composition of the glass, we can begin to understand the origin of the raw materials used to manufacture it and, in some cases, the period when it was produced.”

The glass beads studied, unearthed by archaeological excavations in Dourou-Boro and Sadia, Mali, and Djoutoubaya, Senegal. (UNIGE/Truffa Giachet/Spuhler) These beads have revealed the extensiveness of Medieval African trade routes.

The scientists used laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), which uses very small, fine particles of the material, so they could study the glass beads’ chemical composition without damaging them.

Truffa Giachet says that “it’s also important to understand that the production of glass beads involves several stages, generally located in different places.” The first step of collecting the raw materials may be done in a location separate from the places where the raw glass is made and the manufacturing of glass products takes place. The scientists also had to take medieval trade routes in Africa into account as well to be able to track the origins and movement of the beads. So, they combined “results of the chemical analysis of the beads with historical sources and data from archaeological excavations, thereby obtaining precise information about the origin of the beads,” according to the press release.

Location of the archaeological sites where the plant-ash glasses used as reference were found. (CIA’s ‘The World Factbook’  2020, modified).

Evidence for the Extensive Medieval African Trade Routes

The study’s results, which are published in the journal Plos One, show the glass beads probably originated in Egypt, the Levantine coast, and the Middle East. This handful of beads has helped researchers discover a wealth of information on the nature of the medieval African trade routes which connected regional and international locations. The study authors have explained the path of the glass beads on the African trade routes in more detail, writing:

“All of these ancient beads were exchanged along the trans-Saharan trade routes active during the rise of the first Sahelian states, such as the Ghana and the Gao kingdoms, and show strong similarities with the other West African bead assemblages that have been analysed. Despite the remoteness of their location in the Dogon Country and in the Falémé River valley, the beads studied were therefore included in the long-distance trade network, via contacts with the urban commercial centers located at the edge of the Sahara along the Niger River and in current southern Mauretania.”

Terracotta Equestrian figure from Mali; 13th-15th century; National Museum of African Art (Washington D.C., USA). (Public Domain)

Through the analysis of the glass beads, researchers found evidence of international trade routes connecting Africa with Europe and Asia, which is supported by old Arabic texts discussing the trade routes that crossed the Sahara and connected Africa to Europe and Asia. Anne Mayor, a researcher in the Anthropology Unit in UNIGE's Faculty of Sciences, says the “Trans-Saharan caravans traded horses, guns, luxury objects and salt for ivory, gold and slaves.” Mayor also says:

“The western popular imagination thinks that Africa was disconnected beyond the Sahara, but this was clearly not the case! It was fully integrated into a large international network that linked Africa, Europe and Asia. It was connected to local trade that brought goods of distant origin to the hinterland.”

Of course the medieval African trade routes were also connecting regional and local trade centers, creating a large network which included sub-Saharan rural areas and trans-Saharan trade routes too. However, the researchers found it odd that none of the beads were found to have been produced in Nigeria, the primary production center at the time, suggesting there may have been a preference for the north-south African trade routes “linking the cities located along the Niger River and in southern Mauretania to the Mediterranean basin and the Levant, as opposed to an east-west axis through the savannah regions.”

Finally, the study provides more evidence that sub-Saharan Africa was connected with the rest of the  world through trade routes that shipped all sorts of prestigious goods from one region to another.

Top Image: A new study of glass beads reveals the breadth of medieval African trade routes. Source: frenta /Adobe Stock

By Alicia McDermott