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Author: Mncedisi Siteleki, Researcher, University of Oslo
Original article: https://theconversation.com/ancient-stone-walls-and-power-what-data-science-tools-can-reveal-in-african-archaeology-248603
Visibility has always been important in people’s decisions about where to live and how to arrange their spaces. People make connections with what they can see. Being able to see prominent landmarks, such as certain mountain peaks, rivers or ancestral sites, could help reinforce a community’s connection to its cultural and spiritual landscape.
Some people prefer homes with scenic views, such as apartments overlooking parks or waterfronts, and businesses often choose locations with high visibility to attract customers. In both ancient and modern contexts, visibility plays a key role in how people position themselves in their environment.
That’s why visibility is a useful concept when studying the past.
Archaeologists are interested in what visible and hidden spaces meant to people in long-ago cultures. They have used the idea of visibility to examine things like where settlements were located, socio-political relationships as well as when and where people chose to move.
In the past 30 years, they’ve been helped in these studies by digital tools like geographic information systems (GIS). GIS is a computer system that uses software and data to map, analyse and manage geographic information.
But this method is still underutilised in Africa. It has only recently been taken up and very few visibility studies have been conducted on the continent.
I’m a geospatial data scientist who specialises in uncovering spatial patterns and relationships in archaeological data. I work with the Arcreate project, a group of researchers working on mobility, migration, creativity and knowledge transmission in African societies.
Recently I published a study of 19th century settlements in the Magaliesberg region in South Africa, using GIS tools to analyse what the visibility of the sites was telling us. Were the settlements designed and positioned to be more visible or less? And did this say something about what mattered to the people who lived there?
I hope my study serves as a framework for comparative analyses of other African sites in archaeology and sheds some light on what went into the choice of these locations.
Sotho-Tswana history in southern Africa
In the early 19th century, the Sotho-Tswana farming communities in South Africa’s hilly Magaliesberg region (about 179km north-west of Johannesburg) grew substantially and became more concentrated. Thousands of settlements developed. Among them were the sites I studied: Marothodi, Molokwane and Kaditshwene. They have also been studied over the years by other archaeologists. Today, all that is left of these sites are the stone wall ruins.
Author provided (no reuse)
These settlements were densely populated. They consisted of central kraals (livestock enclosures, or lesaka in the Sesotho language) surrounded by homesteads built of stone. Kaditshwene was the most populous, with about 15,000 residents, and was inhabited by Sotho-Tswana farming communities for the longest time (1650-1828), followed by Molokwane (about 12,000, 1790-1823). At Marothodi (about 7,000, 1815-1823), people produced a surplus of iron and copper (which they traded) as well as keeping livestock.
Cattle were very important in these communities, playing a central role in cultural practices and symbolising wealth. The visibility of cattle kraals is therefore of interest: it may reveal what people wanted others to see and know about their wealth. It adds to other kinds of knowledge that archaeologists have built up about these communities.
Technique to analyse visibility
My study analysed how these 19th century Sotho-Tswana kraals would have been visible from certain points inside and outside the settlement.
I used a computational technique that drew on LiDAR imagery (high resolution imagery created using laser technology) and software called ArcMap.
Visibility analysis finds out to what extent observer locations (kraals) can be seen from different points on a map (LiDAR imagery). It compared the visibility of kraals and other spaces, taking elevation (height of structures like stone walls) as a key variable.
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The analysis was done at two levels: the settlement (a spatial scale of 650 metres) and the household (a spatial scale of 10×25 metres).
At the settlement level, I found differences within and between sites.
Mncedisi Siteleki, Author provided (no reuse)
At Marothodi, two kraals were highly visible from the surrounding 650 metre area and others less so. Overall, it was the most visible settlement, comparatively.
At Molokwane, the central cluster of the kraals was highly visible but visibility decreased with distance within the 650 metre surrounding area.
At Kaditshwene, kraals were not very visible; in fact, this was the case for the settlement overall.
Marothodi, though smallest in size, featured more kraals, while Kaditshwene, the largest, had the fewest kraals.
At the household level, the visibility of kraal outlines at Marothodi and Molokwane was significant both from within and outside the kraals.
So what do these findings tell us?
Space and priorities
My analysis of the kraals quantitatively revealed a correlation between spatial arrangements and social, economic and defensive priorities (which other researchers have suggested before).
Many homesteads and kraals were situated close to each other, emphasising visibility within and around the settlements, which served as symbols of social status and wealth. Larger, more elaborate homesteads, typically belonging to elites, were positioned in a manner that showed off their owners’ power and influence.
However, more settlements with much larger surrounding areas (beyond 650 metres) need to be studied to confirm these correlations in other landscapes.
Photo by P.D. Fredriksen, Author provided (no reuse)
Marothodi had the most visible kraals, likely reflecting its economic focus on the trade of iron and copper. Heightened visibility symbolised wealth and economic activity. Prominent kraals and an open layout suggest deliberate efforts to emphasise trade connections and economic power. The inhabitants evidently wanted to make visible the fact that they were open for business, and that they were doing well from that business.
Read more:
How pots, sand and stone walls helped us date an ancient South African settlement
Conversely, the settlement of Kaditshwene, despite its size, had the least visible kraals. This suggests a defensive strategy aimed at safeguarding cattle from theft during periods of conflict. The undulating landscape and hilltop positioning of settlements reinforced its defensive approach.
Mncedisi Siteleki, Author provided (no reuse)
These observations underscore the dual nature of visibility. It serves as a symbol of wealth and status while also functioning as a tactical asset in defensive strategies. While Marothodi needed to be visible to facilitate trade, Kaditshwene concealed its kraals to be safer during conflict.
In summary, the visibility patterns of these settlements were influenced by a combination of the landscape, as well as social, economic and defensive needs.