The earthworks around Benin City, commonly called the Benin Walls or Benin Moat (Edo: iya)—constitute one of West Africa’s largest documented systems of anthropogenic landscape modification. Built and reworked over many centuries by Edo communities, the inner rings and the wider regional network functioned as defensive works, territorial markers and an integral element of urban and ritual order. Archaeology, historical accounts and institutional surveys confirm their scale and cultural centrality while also revealing how colonial disruption and modern urban growth fragmented and obscured them (UNESCO; Connah; Met Museum).
Origins, chronology and Oba Ewuare
Precise chronology remains a matter of scholarly reconstruction. Oral tradition, travellers’ accounts and archaeology place the origins of the earthworks in the early medieval era, with intensive phases of construction and remodelling occurring through the later medieval period. Oba Ewuare (mid-15th century) receives particular credit in historical accounts for transforming Benin City: he expanded the palace precinct, instituted urban planning measures and deepened or remodelled inner moats and banks that protected the royal enclosure (Connah; Kingdom of Benin studies). Excavations in the 1960s and later revealed deep ditch-and-bank profiles and significant stratigraphy beneath the palace area, demonstrating long-term accumulation and periodic reworking of earthworks.
Form and method: what the earthworks actually were
Field archaeology and geophysical surveys show two related phenomena. First, an inner system of substantial ramparts and deep ditches encircled the royal precinct and densely settled core; in places bank heights reached many metres above the ditch bottoms. Second, a wider regional network, a mosaic of enclosure banks and interlocking moats—extended across the forest and savannah margins to define towns, villages and buffer zones. Institutional summaries describe the regional cluster as covering thousands of square kilometres; cumulative lengths of banks and ditches have been estimated in the thousands or tens of thousands of kilometres when every local enclosure is summed, but these figures aggregate many distinct earthworks rather than describing a single continuous rampart (Met Museum; UNESCO tentative listing; WMF).
Construction used a basic but effective cut-and-fill technique. Workers excavated ditches; the excavated earth was heaped to form embankments. Where required, palisades or thorn barriers supplemented earthen defences. Archaeologists have modelled labour inputs and proposed large cumulative man-hour estimates, but such reconstructions are contingent on assumptions about workforce size, excavation depth, and duration of campaigns (Connah). These models make clear the earthworks demanded sustained, organised labour across generations and speak to strong social coordination rather than to a single “project” undertaken at one time.
Functions: defence, demarcation and ritual order
The earthworks served multiple roles. They functioned as military defences for the palace and inner city, as territorial demarcations for towns and rural domains, and as social and ritual markers that structured ceremonial space. The palace occupied the urban core; roads radiated from the royal compound and gates held specific administrative and ritual functions. Crossing particular thresholds could mark movement between civic and sacred domains; maintenance of the iya formed part of communal obligations and civic identity. Historical accounts and archaeological context tie the moats to systems of labour mobilisation and to the symbolic geography of Obaship.
Colonial rupture and later decline
The 1897 British punitive expedition destroyed the royal palace, looted the bronzes and severely disrupted Benin’s political economy. Colonial restructuring, road-cutting and urban redevelopment undermined the traditional maintenance regime that had sustained the earthworks. In the twentieth century expanding urbanisation and modern infrastructure continued to erode the physical continuity and visibility of many banks and ditches. Today only sections—especially those outside the rapidly developed core—remain recognisable in the landscape. Institutional projects and local activism seek to protect surviving stretches and to document the system for heritage recognition.
Why we must be precise
Popular accounts often frame the Benin earthworks with dramatic superlatives—claims that they are longer than the Great Wall of China or that a single continuous wall once measured 16,000 km. Institutional research, however, emphasises nuance: the landscape comprises many separate enclosures and moats whose aggregate length is vast, but which functioned at village and regional scale as a network rather than as a single continuous fortification. Presenting the system accurately honours both the ingenuity of Edo communities and the complexity of the archaeological evidence.
Author’s note
The Benin earthworks are a major achievement of landscape engineering and social organisation. Archaeology and historical records confirm their extensive and multi-phased construction, their civic and ritual roles, and their partial destruction and dispersal under colonial rule. Accurate interpretation requires distinguishing the inner city defences from the regional network of enclosure banks and acknowledging the provisional nature of cumulative length and labour estimates. Protecting remaining segments and documenting them to international standards remains an urgent heritage task.
References
UNESCO — Benin Iya / Sungbo’s Eredo (Tentative List description).
Graham Connah — archaeological investigations and synthesis (see: Digging Benin City coverage and Connah’s work).
The Metropolitan Museum / World Monuments Fund — summaries on Benin City earthworks and urban form.
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