A new story for Sub-Saharan glass

Materials World magazine
1 Mar 2018

The story of glass working in Sub-Saharan Africa has changed because of a recent excavation. Ellis Davies reports. 

Sub-Saharan Africa has been recognised as a glass workshop for over a century, but, until now, was only thought to have re-worked traded glass following the arrival of Europeans in 1444. 

However, glass beads found in Igbo Olokun, Ile-Ife, Nigeria, by researchers at Rice University, USA, show that areas in Sub-Saharan Africa were producing glass before European influence and are thought to reveal that glass production in Igbo Olokun dates to the 11th through to the 15th centuries AD. This is the first direct evidence of glass production found in the region.

The team uncovered 12,000 beads and several kilograms of debris. Previous excavations uncovered glass encrusted containers and beads, but these were viewed as evidence of the importation and re-melting of glass in the area. This latest discovery and analysis changes the narrative of glass production in Sub-Saharan Africa and could alter perceptions of the global phenomenon of its invention and exchange.

Outside influences

The Portuguese were the first European power to show interest in Sub-Saharan Africa, largely to access the gold trade from Africa and the spice trade from the Indies. First settlement occurred in 1482 with the construction of a fort, El Mina, on the Gold Coast, which became the major centre of Portugal’s gold trade.

Many of the analysed beads from pre-15th century sites in the region align chemically with glass from known production areas in the eastern Mediterranean, the Middle East, or, more rarely, East Asia, which points to far-flung trade connections. Mineral soda glass with high aluminium content found in Sub-Saharan Africa suggest a specific connection with the Indian Ocean trade and was the most common glass type in South and Southeast Asia between the 4th century BC and the 10th century AD, which suggests trade with these regions before European involvement.

Beads previously discovered in the region ‘were consistent with European or near Eastern origins and inconsistent with suggested India origins,’ writes Koen H. A. Janssens in Modern Methods for Analysing Archaeological and Historical Glass, Volume 1, 2013. However, there is also evidence of glass trade with India, and Trans-Saharan trade with Iran and Iraq before the European arrival. 

The history of glass in Ile-Ife

The local population of Ile-Ife, and the wider region of Igbo Olokun, is known to have scoured the area extensively to recover glass. Beads are highly valued and symbolic in the Yoruba culture − in southwestern and north-central Nigeria – today, with beaded crowns denoting political and religious authority. A number of famous brass and terracotta heads found or excavated in Ile-Ife wear beaded crowns, as well as bead necklaces, armlets, and anklets.

Lead author of the excavation’s accompanying paper, and a recent graduate of Rice with a PhD in anthropology, Abidemi Babatunde Babalola, explained the history of glass making in Sub-Saharan to Materials World. ‘Glass started to appear in an archaeological context in Sub-Saharan Africa from the first century BC. By the mid-first millennium AD, glass beads had proliferated the region, with evidence present in burial sites, elite residents, and trade ports,’ he said. 

‘These glass beads originated from the glass workshops in the East of Euphrates − the Islamic world, ancient Egypt, medieval Europe, and South Asia, but were only reworked to modify the shape or finish the unfinished ones at the places of their discovery in Sub-Saharan Africa. Owing to the diverse origin of most of the ancient glass beads known in the sub-continent, the conventional wisdom was that there was no primary glass making − from the raw materials as opposed to re-melting of imports− in Sub-Saharan Africa until contact with the Europeans. The ongoing research at Igbo Olokun, Ile-Ife in Southwest Nigeria has provided a counter-narrative.’

In 2011, excavations at the site in Ile-Ife provided the first detailed description, and potential evidence, of a large glass bead assemblage, including compositional analysis of a sample of the beads. The subsequent analysis of crucibles and other production debris revealed the technology involved in processing a distinctive glass, and results supported the suggestion that this glass could have been made from a raw material, such as pegmatite − extreme igneous rocks that form during the final stage of a magma’s crystallisation.

All is not what it seems

The new research shows that the glass found in the Ile-Ife area contains high levels of lime and aluminium (HLHA). This type of glass is claimed as the earliest form of the material, first made in Mesopotamia and Egypt, with a trace element of cobalt thought to have originated in Iran. However, this distinctive composition has been identified as unique to southwestern Nigeria and a likely result of local primary glass production.

‘The chemical composition of the glass beads consists of high alumina, high lime, low soda, and low magnesium,’ said Babalola. 

He added, ‘This compositional configuration differs from all the known ancient glasses. For example, the Islamic and the Hellenistic/Roman glasses are synonymous with high soda concentration indicating the use of soda rich material as flux. The medieval European glass has high concentration of magnesium, showing the use of wood ash as flux. The glass from Ile-Ife does not fit into any of these compositional groups, suggesting a different origin.’

Researchers analysed 52 glass beads from the excavated assemblage, discovering none matched the chemical composition of any other known glass-production area in the Old World − including Egypt, the eastern Mediterranean, the Middle East, and Asia. The glass’ composition also reflects local geology and raw materials.

Wider influence

The study has implications for the development and innovation of glass in general. ‘Since the invention of the first man-made glass, the composition has been changing from region to region,’ said Babalola. ‘This study has improved our understanding of the kind of glass made in West African Sub-region about 1,000 years ago. The type of glass made in Ile-Ife can now be added to the global data base of glass as a variation in the technology as it moved across the globe.’

The study also informs the history of innovation, technology, and development, and re-addresses aspects of the regional, interregional, and intercontinental history of interaction. ‘Our findings also contribute greatly to the study of early commerce. We now know that forested zones of West Africa also supplied prestige goods, in the form of glass beads, to the trans-Saharan trade,’ Babalola said.

Establishing that the glass was locally made, using local raw materials – pegmatite as source of silica with snail shell added as source of the lime – is not the end of the study, Babadola said. The team will continue to research new questions that have arisen following their discovery. ‘There is still a lot we are yet to understand about the organisation of production at the site. Were there other glass workshops within ancient Ile-Ife? What tools were used in production? Were the crucibles made at the site? Where was the clay for the crucible sourced? Did other craftsmen co-exist with the glass makers? Or what was the relationship between the glassmaker and other craft specialists? These questions, among others, will be our focus as we continue with the research.’