Vol. XIV, Issue I (Winter 2007): Nigerian Enclosures


Gloria Emeagwali
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Table of contents

Editorial- Aribidesi Usman


The Historical and Archeological Significance of Koso Wall, Old Oyo National Park, Nigeria - David Aremu

Enclosed Walls in Northern Yorubaland, Nigeria – Aribidesi Usman    


Walls have for some time fascinated archaeologists and historians working in the early and late periods of African history. They can inform us not only about the settlement that is enclosed, but also about why, when, and how the wall was built. This issue of Africa Update focuses on West African enclosures or walls with specific reference to the Yoruba polities of the Oyo Empire and the periphery. Dr. Aremu, an archaeologist and specialist in cultural resource management gives a clear insight into the historical and archaeological importance of the ancient Koso wall, and the need to preserve the relics for future generations. Oyo Ile or Old Oyo is an ancient Yoruba city and former capital of the Oyo Empire. The Oyo Ile site is currently a part of the Upper Ogun Games Reserve established by the Nigerian government. The ancient Koso wall is seen as an additional tourist resource to Oyo Ile in the Old Oyo National Park. This article is an account of the reconnaissance work carried out by the author at Koso and the associated site, Bara. In the historical context of the Oyo Empire, Koso was a capital city of Oyo, while Bara was the burial site of Oyo kings. Beside Koso, Oyo established other capital centers such as Oyo Ile and Igboho. The author presents a brief history of Koso and its association with Sango, the deified Yoruba deity.

Yoruba oral traditions often identify Sango as one of the early kings (Alaafin) of Oyo-Ile. He was a great warrior and magician who, it is claimed, had the power to attract lightning, with which he allegedly vanquished his enemies on the battlefield. The circumstances surrounding Sango’s death and deification are not clear, but as Dr. Aremu alleges his subjects forced him to abdicate after becoming tired of his political intrigues and military escapades. Sango worship was a state religion from the 17th century to the early 19th centuries, when the kingdom was at the apex of its power.
Koso wall is a multiple wall system built of mud and consisting of both outer and inner walls. The innermost wall which the author investigated varies in length from 3 km to 4.5 km in different location at the site. The innermost wall consists of three categories: standing mud walls, mud walls from ground level and heap or raised ground. Koso wall enclosure, like other West African walls, was built for different purposes. The construction of city walls was to counter aggressions and protect communities from invaders.

The location of Oyo close to non-Yoruba groups like the Nupe and Borgu, and the frequent military encounters between these polities, are relevant to the understanding of the Koso walling system and the shifting capital of Oyo. However, the enclosure walls may have served other functions such as political, commercial, and ethnic purposes. The author suggests that the investigation of Koso should also involve excavation - to provide datable materials and other finds, for a better understanding of the lives and condition of people that made Koso and its environs a home. In addition to the walls and other cultural remains at Koso, the author also looks at the natural resources (e.g., geology, fauna, and flora) at Koso and its environs as additional attractions that must be protected for the present and future generations.
Cultural resource management in Nigeria is still essentially a federal government affair. There is lack of awareness at the local government level of the significance of the indigenous cultural materials of the people. Nigerians who are unaware of the value of cultural objects are less sympathetic to the cause of preserving them.

The standing mud wall of Koso, the only standing ancient city wall monument in any part of the southwestern Nigeria, is a rare cultural heritage that should be protected. The walls are deteriorating as a result of human and natural factors. Dr. Aremu calls for a proposal that will make ancient city walls such as Koso part of UNESCO’s most endangered sites, as done in other countries of the world such as Peru, where “earthen sites or mud walls account for 10% of the UNESCO World Heritage list.” The author also suggests ways to improve the condition of Koso walls in a way that will promote tourist attractions. This is a challenge to the management of the Old Oyo National Park and other departments such as the National Commission for Museums and Monuments which engage in preserving and protecting the country’s cultural resource.

Guest Editor
Dr. Aribidesi Usman
African & African American Studies
Arizona State University

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The Historical and Archeological Significance of Koso Wall, Old Oyo National Park, Nigeria

Dr. David A. Aremu
Department of Archaeology and Anthropology,
University of Ibadan, Nigeria.

Old Oyo National Park, like Yankari National Park in Bauchi, Nigeria, has numerous archaeological and historical sites that provide additional attractions to tourists with interest in wildlife (Aremu 1999). Old Oyo National Park is located between latitude 8o 15’ and 9o 00’ N and longitude 30 35’ – 4o 42’ E. It has a total area of 2,512km2 and an average rainfall of 1,100mm per year. Koso and Bara archaeological sites are to the northeast of Oyo Ile and a full acquisition and control of the area would increase the tourist resources of Old Oyo National Park. The Park is surrounded by eleven Local Government Areas, namely: Atiba, Atizbo, Irepo, Iseyin, Itesiwaju, Iyamopo/Olorunsogo, Oorelope, Orire, Oyo West, Shaki East (all in Oyo State) and Kaiama in Kwara State.

Old Oyo National Park has five ranges. They are Oyo Ile, Marguba, Tede, Sepeteri and Yemoso ranges. The Park is established to preserve and protect the cultural remains of the ancient Oyo Empire. It is also to conserve and protect the indigenous Nigerian flora and fauna resources in this area for the benefit of present and future generations. Oyo Ile range contains historical, archaeological and monumental objects and some wild animals. Marguba, Sepeteri, Tede and Yemoso ranges have more wild animals than Oyo Ile.

Old Oyo National Park has become better known within the past five years in Nigeria. The tourism unit has succeeded in attracting lots of tourists from within and outside Nigeria in the recent past (Jeminiwa 1999: Pers. Comm.) with its mobile labeled vehicles, various handbills, newspapers and periodicals publications and sponsored television advertisement programs. As part of the development programs of Old Oyo National Park, Oyo Ile was extended to Koso and Bara in March 1999. To better determine the potential for tourism the park management requested for an archaeological reconnaissance of Koso and Bara. This paper is a report of the reconnaissance of Koso and the need for preservation of its cultural relics.

According to oral tradition of Oyo people, Koso was a former capital city of Oyo Empire. There are three earlier capitals near the Niger River. The people moved to Koso for security reasons and settled on Koso Hill and below the Bara Mountain. They later moved further South to Oyo Ile, then to Ipapo Ile, Igboho, and back to Oyo Ile before they finally settled at the present Oyo, 52km northeast of Ibadan (Abimbola 1964; Agbaje Williams 1989; Aremu 1997; Babayemi 1980; Morton-Williams 1967). Bara is about three kilometers northwest of Koso. It was a settlement site where late Alaafins were buried. Extending Oyo Ile to Koso and Bara would provide some of the rich historical, archaeological and cultural materials of the ancient Oyo Empire.


The Yoruba called the Niger River “Odo Oya” after Oya, the wife of Sango. The oral history indicated that anytime Sango was traveling to the north he used to meet this beautiful woman named Oya at the bank of the Niger. After falling in love with her, Sango started showering her with gifts whenever he traveled to the north. These love overtures eventually led to marriage. After their marriage Sango discovered that Oya had some supernatural powers and this, in conjunction with her beauty made Sango love Oya more than his other wives. As a result of rancor in Oyo between Gbonka and Timi, Sango, the fourth Alaafin of Oyo, was forced out of his domain and all his wives and people left the town with him. Because of the humiliation, Sango committed suicide and many of his followers went back to Oyo. Oya, his faithful wife did not go back because this would have been a disgrace had she returned to Oyo.

She decided to go very far from Oyo, by following the forest until she got to a certain area now called Ira, southeast of Oyo in Oyun Local Government Area of Kwara State. There is an Oyo shrine at Ira, located south of the town. The Ira people claim that their ancestor came from Oyo.

Sango and Oya have been deified and have become one of the most famous Orisas in Yorubaland. These historical events have led to a common saying in Oyo that:

“Oya wole Nira
Sango wole ni Koso.”

Oya entered the ground at Ira (i.e. died)
Sango entered the ground at Koso (i.e. died)

Our archaeological reconnaissance was carried out at Koso. Among the present Oyo, Igbeti, Kosa, Bani and other neighboring towns there is the fear that nobody could climb Koso Hill because it was where they claimed that Sango died. They believed that his spirit might still be around and might harm anybody that got to the site. It was considered as part of the objectives of this research to find out where Sango died at Koso.

In March 1999 we climbed the hill to where it is claimed that Sango died. The place is a big rock outcrop with another on top of it forming a ‘T’ shape. Contrary to the people’s speculations, beneath the site is a flat rock outcrop on which one might spread farm products. There are potsherds scattered around the area and a mud wall protecting the northern part of a rock shelter, south of the flat rock outcrop. Sango might have hung himself and died but it might not be on the ‘T’ shaped rock outcrop.

They claimed he died on Koso Hill and that Koso site was named after the incident of Sango’s death. His favorites disputed how he died. Some said “Oba so” (the king hung), while other said “ Oba Koso” meaning “The king did not hang”. Thus, the name ‘Koso’ abbreviated from ‘Oba Koso’ emerged. This implies that the site might have been called another name before Koso. None of our informants could clarify this assumption.

Sango as Alaafin of Oyo built and left behind a virile capital city at Koso. He might have enjoined the cooperation of his subjects as their king which must have helped to achieve the building of the various defense walls at the site. It is possible that more than one Oba might have reigned at Koso apart from Sango. The contributions of all such rulers might have led to the development of Koso before it was abandoned.

After the death of Sango and Oya, both were deified and are still worshipped. In life both exercised political power and influence over the people, and in death they were deified and worshipped as orisas. It is a way of honoring past heroes by preserving what they left behind.


Igbeti is one of Old Oyo National Park’s Patrol Post and it is about forty kilometres to Oyo Ile. A new and more accessible Patrol Post is built at Awodi, ten kilometres to Oyo Ile for administrative convenience and to prevent poaching activities. Iron slag is scattered in the bush opposite the Patrol Post which is evidence of iron smelting in the area in the past. There are Fulani farming settlements between Oyo Ile, Koso and Bara. These are Budo Are (nearest to Oyo Ile at the northeast), Budo Audu (nearest to Koso from the west), Onigbangba (closest to Bara) and Elenre about four kilometres northwest of Koso. The Fulani farm and graze their cattle in this area. The nearness of these settlements to Oyo Ile Park is causing a poaching problem to the Park. The park rangers have made several arrests and prosecuted many. The poaching problem has been reduced a little after the park management adopted the system of dialogue, an enlightenment campaign and friendly attitudes toward the surrounding population. 


The vegetation in the area contains remnants of the rainforest. The present day vegetation is the result of human activity of land cultivation, cattle grazing, and severe annual bush burning. The southern guinea savannah has a similar general appearance of the derived savannah. The area contains a whole range of vegetation types including a riparian forest, a concentration of herbs trees and other woody plants and grasses. Some of the trees and shrubs have twisted and gnarled trunks as a result of frequent fires which have checked their growth. The bark of most species is very thick, usually more than 1cm, and this probably accounts for their tolerance of fire. The trees include Afzelia africana (mahogany bean), Elaeis guineensis (oil palm), Butyrospermum paradoxium (shea butter) with deep fissuring, Daniellia oliveri African (copaiba balsam), Parkia clappertoniana (African locust bean) and Vitex doniana (black plum). The farmers cultivate yams (Dioscorea spp.), cassava (Manihot esculenta), maize (Zea Mays), guinea corn, and vegetables such as okra (Abelmoschus esculentus).

The mammalian fauna found in this area include baboon, (Papio anubis), the red monkey (Erythrocebus patas), crawshay’s hare (Lepus crawshayi) and giant rats (Cricetomys gambianus). Large herbivores include waterbucks (Kobus defassa), Kobs (Kobus kob), bushbucks (Tragelaphus scriptus), roan antelopes (Hippotragus equinus), and warthogs (Phacochoerus aethiopicus). Carnivores include spotted hyenas (Crocus crocuta), wild dogs (Lycaon pictus) and lions (Panthera leo).


Koso is a hilltop settlement which extends down the hill to the west and the south. The hill is separated to the north and south with a gap which is occupied by a defense wall. There is evidence of settlement on the hills at the two sides. The people claimed that Sango died in the north. In this area are two rock shelters – one with mud walls that served as partitions in the rock shelter, and inside the other, a piece of rock which might have been used as a stool. Other cultural materials in the area include grinding stones, house foundations, rock hollows, and potsherds. In the southern hill the house remains are more pronounced with partitioned room walls still discernible. Most of the houses were built into rocks serving as side walls. The rooms are 4 m and 3 m long and wide respectively and are rectangular in shape. There are many protruding granite rock outcrops which might have attracted people to this area.


Koso settlement is surrounded by three walls. The innermost wall was investigated in March 1999. From the survey of the wall to the west, the outermost wall is 3.6 km. The outermost wall continued northwards towards Bara, while the wall to the south might have extended to Oyo Ile (Olatuboson 1999: Pers. Comm.). The innermost wall in the North is 3.8 km, West 4.3 km., East 4.4 km, and South 4 km. The walls are in three categories of deterioration as at the time of the fieldwork. These are: (1) standing mud walls above one metre to seven metres high (2) mud walls of zero to one metre high, and (3) heaps of raised ground indicating the wall path. These are discussed below.
(a) Standing Mud Walls
These are more pronounced in the northeast where we have Koso Hill, than in any of the other sides of the site. The height ranges from 5.1 m to 7 m and 1.6 m in thickness. They range from nine to thirteen courses on top of each other. The mud walls have attractive intrusions of potsherds, quartz, quartzite and granite rock. Two meters from the ground floor are holes 10 cm in diameter, created through the wall at 1 m intervals. Ajayi and Smith (1971) were of the opinion that where such occurred on the walls of new Oyo, Osogbo, Ikirun and Ijaye guns could be fired to the enemy through holes. While that might be possible during the period of gun use (A.D 15th century and above), Koso might predate such a period, and the holes might not be used primarily for firing guns at enemies but for use within the wall to view opponents from outside as a security measure.

(b) Mud Walls
Walls from ground level to 1 m high occurred on every side of the settlement. They indicate the last stage of destruction of the walls wherever they occurred. They exhibit the same character of thickness as potsherds, quartz, and quartzite intrusions.

(c) Mounds
Raised ground or mounds were observed along the wall path where the walls had been destroyed, on both sides of the wall. The collapsed wall might have created humus soil along the wall path on the raised ground. The trees grew in sequence along the path as if planted deliberately. Porcupines dwelt inside the raised ground. Spines of porcupines killed by hunters were found during the survey along the northern and western walls. Digging of the walls by hunters, to kill animals, endangered the preservation of Koso Wall. The Archaeological Resources Protection Act and the National Historic Preservation Act should be enforced to prevent further destruction in this area.

The standing mud walls at Koso constitute a rare cultural heritage that should be preserved. They cover a length of about 150 m stretching east-west. There is no occurrence of such standing wall monuments in any part of the southwestern Nigeria. The reconstruction and preservation of walls on Koso Hill to the south should be carried out. These are about 180 m south of the standing walls. The cultural features on Koso Hill to the north would add to the many attractions at the site. Apart from mud walls, in a few places in the west, there are other cultural materials along the wall path and in the settlement, such as potsherds, ash mounds, grinding stones, rock hollows, rock shelters, some flake tools, quartz, quartzite and laterites.


The settlement enclosed by the walls is more important than the actual earthworks. In a general sense any fortification serves as an indication of the size, wealth and importance of the town or city it enclosed. It provided security for the lives of those within the wall. Koso is no longer inhabited. The architectural building of the walls, its size and boundary, the settlement remains, and the cultural materials at the site are sources of information about the lives of the people who lived in the area. The walls serve as people’s cultural heritage which if well preserved can provide more information about the past in the present and the future. The walling city might have enclosed people of the same historical and cultural background. Oral traditions suggest that the former inhabitants of Koso were Yoruba of the Old Oyo Empire.

Koso might have been an important commercial centre. One of the important reasons for the construction of walls and embankments around settlements was to protect commercial activities. As a result of a flourishing trade, towns were at war with their neighbours in an attempt to gain control of trade routes and commercial centres. Kano and her neighbour Katsina by A.D. 1000 to 1500 were the strongest commercial centres of Hausa land and their peace was constantly disturbed. They were forced to construct a civic defense to protect the operation of both regional and inter-regional trade and commerce which constituted the essential life blood of the city.

In history it is recorded that Oyo Ile, Kano, Zaria, Ife, Benin and Ijebu Ode were, one time or the other, centres of commercial activities (Adesina 1979). Oyo Ile’s commercial position may have started at Koso before the people moved to Oyo Ile. Towns enclosed by walls and embankments usually served as centres of political power. This was true of Koso and Oyo Ile which were capital cities of Oyo Empire in succession. In order to defend the city against external aggression, walls and embankments were built. The construction of walls and embankments of Zaria, Kano, Sokoto, and Katsina brought peace to the towns thereafter. The walls were built as a means of repelling possible military attacks. The walls were of special importance in its functions as political and military enclosure. People who lived in settlements near the walls were allowed into the city during war. The city wall was constructed to provide protection against possible external aggression.

It was in the process of establishing kingdoms and providing stable commercial centres with maximum security for smooth running that defense was constantly extended and maintained. The walls and embankment of Koso help to throw more light on the history of the Oyo Empire. The existence of the wall has given us a concrete location and the physical extent of this capital city of Oyo Empire. Excavation across the inner wall might give some important information on the chronology and other aspects of the lives of the former inhabitants of the site. Connah’s excavation of the innermost wall of Benin near Ogba road gave an insight to the practice of iron smelting and the period it started. It has also been possible to date Oyo Ile through the pottery type incorporated in the walls. Koso walls have become an irresistible tourist attraction because of its height, thickness, architecture and history, important reasons for advocating the preservation of the cultural remains.


Koso walls are exposed to some dangers which led to the collapse of parts of the wall. Each successive rainy season washed the wall from the top to the foundation level eroding parts of it. Trees that grow near the wall have become very big and the branches and roots have destroyed parts of the wall. Hunters excavated various parts of the wall while hunting for small games without any regard for the preservation of the wall. Bush burning is practiced in the area annually and at every season the walls are burnt since they are often covered with bush. Without any preservation measures to prevent further destruction, all the walls will be gone without a trace.

The National Commission for Museum and Monuments has proposed Old Oyo as one of the Nigeria’s UNESCO World Heritage sites. In other countries such as Peru in South America, earthen sites or mud walls like the Old Oyo walls account for 10 percent of the UNESCO World Heritage list. A renewed commitment to the conservation of earthen architecture and the promotion of its values is essential for this heritage to be universally recognized as an area of study and of professional practice as suggested by ICCROM (Little 2001).

Old Oyo National Park should be given needed Federal Government support to preserve and protect Koso wall henceforth. Immediate task of the Old Oyo National Park is clearing the surrounding vegetation of the standing walls to a distant of four meters each from both sides. The clearing should be done on a regular basis. This will prevent annual burning of the wall and provide a cleaner environment under which the walls would be more visible to tourists. The trees and other disturbing roots should be removed to prevent damage to the walls. The walls that are very weak should be supported by pillars of mud walls constructed by local bricklayers knowledgeable in mud building construction. The walls may be roofed with grass and supported with wooden poles.

The Great Zimbabwe stone structures have undergone various preservation measures. Further advice could also be sought from those who had worked on the preservation of the Great Zimbabwe stone structure to compliment whatever is being done in the interim. The Federal Government should also enforce The Archaeological Resources Protection Act and The National Historic Preservation Act all over the nation and in the Koso area of Old Oyo National Park, in particular. They should empower the National Commission for Museum and Monuments (NCMM) to carry out a nation-wide conservation and restoration of cultural properties, by initiating, developing, promoting and facilitating conditions for such conservation and restoration. The NCMM should have architectural and conservation units to deal with such matters.


Innumerable artifacts of Nigerian cultural heritage have been destroyed due to ignorance on the part of the custodians, irresponsibility of cultural administrators and unsupportive attitudes by government. Many reports have been made about artifacts of Nigerian cultural heritage which had been allowed to waste away. The case of Koso wall should not suffer the same fate. The maintenance of the road to Koso should be considered important and would make the preservation of the site meaningful. The beauty of Koso rock outcrops and rock piles and the architectural fascination of the standing mud walls are enough to attract tourists to the area. Preservation of cultural and natural resources is the key to successful tourism in Nigeria. More tourists would be encouraged to visit the site if the cultural and natural relics are better preserved.


Abimbola, W. (1964). The Ruins of Oyo Division. African Notes 2, 1, 16-19.
Adesina M.O. (1979). City Walls and Embankments in the Savanna and Forest Areas of Nigeria. B.A. project, Department of Archaeology and Anthropology, University of Ibadan.
Agbaje-Williams, B. (1989). The Discovery of Koso, an ancient Oyo settlement.
The Nigerian Field 54, 123-127.
Ajayi, J.F.A, and Robert Smith (1971): Yoruba Warfare in the Nineteenth Century. Ibadan: Ibadan University Press.
Aremu, D.A. (1979). “Preservation of Archaeological Resources in Old Oyo National Park: A means of promoting Cultural Heritage and Tourism in the Park.” Report Submitted to Old Oyo National Park, Nigeria.
Babayemi, S.O. (1980). The Fall and Rise of Oyo, C.1760-1905: A Study on the Traditional Culture of an African Polity. Ph.D. dissertation. University of Birmingham. U.K.
Connah, G. (1975). The Archaeology of Benin. London: Oxford University Press.
Little, T. (2000). The Architecture and Archaeological Site Programme in International Centre for the Study of the Preservation and Restoration of Cultural Property (ICCROM) Newsletter, October 2001, 27.
Davidson, B. (1965). Old Africa Rediscovered. London: Oxford University Press.
Morton-Williams, P. (1967). The Yoruba Kingdom of Oyo, in Forde, D. and Kabemy, eds., West Africa Kingdom in the 19th Century. Oxford: Oxford University Press.

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Enclosed Walls in Northern Yorubaland, Nigeria

Aribidesi Usman, Arizona State University

Fortifications, especially enclosing walls, are common features in large African political centers and have been widely studied (Connah 1975; Ozanne 1969; Posnansky 1969; Soper and Darling 1980:61-81). African city walls consist of enclosures, either single or multiple, that entirely or partially surround habitation. Various materials were employed in their construction. This includes stone, mud, or earth with banks and ditches, timber stockades, or naturally grown vegetation. The increasing interest in the periphery of large Africa polities has revealed that the culture of walling system was more widespread than previously thought. Enclosure walls like those in large political centers have been found among small-scale African societies. It appears that the same forces and needs which made construction of enclosure possible at large centers were also at work in the periphery. Archaeological investigations conducted in Northern Yorubaland have resulted in the discovery of pre-19th century fortifications, similar to those associated with large polities of Ife, Benin, and Oyo. Northern Yorubaland encompasses the present-day Kwara and Kogi States of Nigeria. The region comprises several ethnic groups, notably the Yoruba, Nupe, Baruba, Ebira, Igala, and Kakanda. In the past, Northern Yorubaland was characterized by the movement of peoples, culture contact, and confrontations which were sometimes endemic, and the social consequences which flowed from this.

This article is the result of some work carried out in Igbomina area of Northern Yorubaland. Fortifications have been found at several settlements in the region, but two of these, Gbagede and Iyara, located within the Igbomina area of Northern Yorubaland are discussed here. The intent of this paper is twofold. The first is to provide a survey description of the walls, and the second is to explore the functional interpretations of the walls. The study of fortifications in this part of Yorubaland will provide an understanding of the nature of Old Oyo’s northern frontier and the prehistoric social relations in the area, especially between Oyo-Igbomina, and the Nupe.


Gbagede site is located about 3.2 km northeast of Ajasepo town in Kwara State of Nigeria. The site is situated on relatively flat land bounded to the west by the Osin River which flows to Omupo town, and on the east by river Egui. Iyara is located about 2.2 km northeast of Ajasepo town and about 1 km southeast of Gbagede site. The sites are situated on a relatively flat terrain with derived savanna type vegetation. The small Igbinla River enters Iyara site from the southeast and flows toward the northwest where it escapes through the wall toward the direction of Gbagede. The first survey of Gbagede and Iyara walls first carried out in 1995, involved taking measurements between points along the wall using tapes, ranging poles, and a prismatic compass. The distance between one point and the next is 30 m, except at corners and near gates. Early in the year 2003 these walls were re-examined using GPS equipment.
Gbagede is a large pre-19th century settlement with an enclosed wall of mud, occupied between 1390 and 1795 (Fig. 1). From the 2003 survey estimates, the height and width of the walls range between 1 and 3 m high and 4 and 6 m wide. Three main entry gates, probably with sentry, and two or three minor entrances were associated with Gbagede wall. There are excavated holes or pits placed randomly inside the wall. These pits are in most cases with exposed granites and may have served as water reservoirs for the inhabitants of Gbagede. Inspection of the southern and eastern walls revealed stones and potsherds eroding out of the wall. These may have been incorporated into the wall during construction. The survey of Gbagede indicated a single wall system with a circumference of about 3.4 km, while the site area was estimated at approximately 612,360 m2 or 0.612 km.2 In the case of Iyara, the wall is rampart with two main entrances, and a continuous ditch located outside the wall (Fig. 2). The depth of the ditch varied from one section of the wall to another with the deepest about 1.3 m. Such a deep ditch was unique of a rampart built wall. Generally, the wall height ranges between 1.2 m to 2.0 m, while the width was between 4.3 m to 5.5 m. The Iyara enclosure is estimated to be about 2.8 km in circumference. The name Iyara seems to be synonymous with the physical feature, the conspicuous walling system. Iyr or Yr in Yoruba means trench, or ditch, behind the walls of a town.

Sociopolitical Relations

The sociopolitical circumstances which necessitated the construction of enclosed walls in Northern Yorubaland involved the consideration of two forms of social relationships in the region: the Oyo-Igbomina relationship and the Yoruba-Nupe relationship. The rise of Oyo was related to the formation of links with periphery groups. The establishment of such links usually came as a reaction to some external or internal threat which necessitated the demonstration of unity in the area. For Oyo, such a circumstance arose with the Nupe invasion of Oyo-Ile in the 15th century. The expansion of Yoruba (Oyo) was an outgrowth of the formation of alliances between the Oyo and the Yoruba frontier groups whose thrusts into Northern Yoruba were the most penetrating when the tensions between the Oyo and the Nupe were high. The strategic importance of Igbomina to Oyo in terms of political or military purposes, appear to have constituted an important basis for alliances. Igbomina was a frontier area occupied during a geographical expansion of the Old Oyo in the 16th century, an expansion which furthered the political and military interest of the state. The Igbomina-Yoruba was located near the Nupe ethnic group, who lived both on the right bank of the Niger downstream of Jebba and to the north of the Niger River. The Northern Yoruba society, located between the Nupe and Old Oyo had the strategic advantage of protecting Oyo's northern frontier.

The Nupe ethnic group earlier divided into several small chieftaincies and later united in a single kingdom (Elphinstone 1921) and lived to the north of the River Niger. But there was also a Nupe province, centered on the town of Ogudu, on the right bank of the Niger downstream of Jebba close to the Igbomina. While it may be very difficult to understand the events of this period, it has been suggested that some of the areas in Northern Yoruba were also inhabited by the Nupe; that they were subsequently dislodged and partially absorbed by successive waves of Yoruba immigrants first from Ile-Ife and then from Oyo-Yoruba speaking areas (Adepegba 1982). This claim would seem to be supported by the soapstone figures found in Igbomina areas which exhibited both Nupe and Yoruba culture traits (Stevens 1978). It appears that both cultures (Yoruba and Nupe) may have co-existed until certain time, probably by the 16th century when the Nupe were displaced by the expansion of Old Oyo (Obayemi 1976), and inter-group violence with the Nupe began to pose an ever-present threat to the well-being of the people and the survival of Oyo’s northern frontier.

Functional Interpretations

The study of site enclosures reveals how an architectural feature might have functioned in regard to prehistoric social relations. Here, I will explore the applicability of one of the most commonly applied functional labels, that of defensive function, as it relates to Northern Yorubaland. Warfare was a major unpredictable environmental variable in the region. Therefore, there should be a correlation between those elements of the cultural system's environment which are unpredictable and evidence of a society-wide organizational activity to deal with them. A good example of preventive action taken by the people was the construction of fortifications. Thus, important towns, and even some larger villages in Yorubaland were surrounded by a roughly concentric 'wall' of dumped earth or, less often, by a stockade (Smith 1973). As well as providing defense in depth, wall and ditches offered protection to an army forming up for attack between the walls.

Oral traditions, dating as far back as the 16th century provide historical evidence of military invasions of the Yoruba by the Nupe. Nupe influence began to grow in the area when attempts by Old Oyo to build a military outpost in Igbomina failed to check Nupe incursions (Law 1977). The Nupe intensified their incursions in Northern Yorubaland in the mid-18th century when the constitutional crisis in Old Oyo began to pre-occupy the aristocracy and reduce Oyo's control in the north. This information includes wars fought, and destruction and abandonment of settlements well remembered by elders. The Nupe incursions of the mid-18th century became particularly noticeable during the reign of three Nupe kings: Etsu Jubrilu (1744-1759), Majiya II (1769-1777), and Mu'azu (1779-1795) (Elphinstone 1921). Although these Nupe military encounters can be described as 'smash and grab' operations with little consideration for long-term exploitation, they continued well into the 19th century when the Fulani conquest or rule was superimposed on the northcentral Yoruba.

A version of oral tradition suggests that the Iyara site was a war camp founded by one Balogun Adelani, a warrior who migrated from Old Oyo. Wars that were fought by this founder and his successors are given as Erinmope, Adamu, Adunbi, and Agannigan (where men perforated their ears). It is not known when these wars were fought, though some of them appear to refer to the Yoruba civil wars of the early 19th century, following the fall of the Oyo Empire. The second version of oral tradition suggests that the site was originally inhabited by the Nupe, and abandoned when the Oyo immigrants arrived in the area. However, there is no excavation material yet to confirm or dispute these assertions.

Further support for the defense interpretation of the enclosed wall is provided by excavated iron arrowheads from some Igbomina sites, which may have been utilized in war (Usman 2003). Oral tradition in Northern Yorubaland refers to the use of bows and arrows by the Borgu, nearby neighbors of the Oyo, in the time of Alafin Ofinran, who probably reigned at Oyo around the middle of the 16th century (Smith 1967). The excavated iron arrowheads from Igbomina have been dated to between the 15th and16th centuries AD, and appear to suggest that the weapons must almost certainly have been used by the Yoruba-speaking people in the area by the 16th century.

In addition, walls may act as spatial demarcation, social regulation, as well as for privacy of the political elites (Adler 1990; Kane 1989; Ozanne 1969; Tringham 1972:470). In describing Ife walls, for example, Ozanne (1969: 32) claimed that, “the communities . . . must have had a more elaborate social structure than that of autochthonous hamlets of early life. The fact of building a wall indicated a single though probably segmented, polity, in which relations must have been carefully ordered.” By demarcating a group’s ‘place’ in the environment, a boundary becomes a symbol of the social and political group (Wilson 1988: 60) and may function to reinforce its identity. The fact that residential groups chose to demarcate their settlements with walls implies that the space and its contents were highly valued (Tringham 1972: 470). Some local elites in Northern Yoruba may have taken advantage of their relation with Oyo to replicate the walling culture of the large polity on the frontier. The character of Gbagede wall may be related to the sociopolitical importance of the settlement as a ‘capital’ or head town in the area where the king, Olupo, resided. The Gbagede and Iyara walls may have political connotations, such as the presence of a highly valued political institution, and as an enhancement of privacy and prestige, while signaling the existence of a high degree of political and social cohesion. Whatever the situation in Northern Yoruba, the walling system, like in the large African political centers, were major projects that would have required discipline and planning, as well as leaders with the ability to marshall the labor and provide food for the construction.


The geopolitical situation in Northern Yorubaland, the encircling nature of walls, ditches, settlement abandonment, and excavated 'weapons' of war have helped in suggesting a climate of hostility. It is possible that warfare, exemplified by the wall systems, suggests the collapse of a system of balanced but competing Yoruba and Nupe polities. However, this factor must be understood in relation to other factors. The Igbomina may have constructed enclosed walls and evolved towards increased ‘centralized’ control and ‘hierarchy’ in reaction to the Nupe on its borders. The walls were part of the regional socio-political and economic change that occurred in Yorubaland and elsewhere in West Africa from the fifteenth century.


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