Pẹhẹ, an infectious disease of the respiratory organs, ravaged the capital of the Ọ̀yọ́ Empire in 1831 (Johnson 1921, p. 215–216; Fig. 1). It reportedly killed thousands of people. The king, Aláàfin Májòótú, was among its victims. The pestilence of 1831 seems to be a culmination of the four-year recurrent epidemic outbreaks in the capital. In his visit to Ọ̀yọ́-Ilé in 1827, Cornish explorer Richard Lander observed that those suffering from infectious disease(s) were removed to an isolation center, in a bush, about half a mile from the city. The sick were placed “underneath the branches of trees…” (Lander 1830, p. 219). The law prescribed that their nearest of kin must provide them with food and water. Unfortunately, the year 1827 was unlike any other time in Ọ̀yọ́-Ilé. The metropolis was already debilitated by famine as a result of drought and political unrest that began about a decade earlier. The pandemic was, therefore, a rub of salt in the wound. There was little food for the healthy. Richard Lander noted that many of the sick people in the isolated center, who were of poor backgrounds, died from starvation rather than the contagion. Not surprisingly, social class mediated the impacts of the epidemic, in terms of the quality of care for the sick and the rate of survival.

Fig. 1
figure 1

The Ọ̀yọ́ Empire, 1776

The COVID-19 pandemic and its psychological and social consequences, not to talk of political and economic impacts, give some new perspectives on how to imagine epidemics in the past societies. Africa has had its share of microbial attacks, neither more nor less than other climes. But the details of these epidemic outbreaks are usually missing from our understanding of deep-time African history. The reason for this is not far-fetched. The ecology and material evidence of microbial epidemics are difficult and expensive to pinpoint in archaeology (Pfeiffer, this forum). Instead, we have sharpened our methodological tools, especially with archaeobotany and geoarchaeology, to detect droughts and other environmental perturbations. As a result, we have developed great models and interpretation frameworks for understanding the intersections of drought and sociopolitics and vice versa (e.g., Logan and Stahl 2017). Both droughts and infectious diseases are products of ecological perturbations, but they cannot be understood outside the sociopolitical and environmental contexts. Those contexts aggravated the impacts of the 1827–1831 cycle of epidemic outbreaks in Ọ̀yọ́-Ilé. The health crisis also significantly distracted from finding solutions to the political and environmental problems of the time. Those problems included intra-elite political conflict in the metropolis, the underclass and provincial rebellions in the empire, external aggression, multi-year droughts, and debilitating famine (Ogundiran 2020). Before the epidemic of respiratory infections descended on the metropolitan area at different periods between 1827 and 1831, the capital had lost most of its workforce due to the underclass rebellion of 1817. The provincial revolts had also reduced the empire to about one-third of its size, and drought and famine had emaciated the entire population. Hence, although Pẹhẹ reportedly killed thousands in the metropolis in 1831, the city had already lost more than half of its ca. 100,000 people to migration and untimely death due to the aforementioned crises. The units of our archaeological observation cannot be as fine-scaled as the eyewitness accounts reflected in Richard Lander’s travel accounts and Samuel Johnson’s magisterial history of the empire (Johnson 1921; Lander 1830). However, those of us working on the archaeology of the recent past have the advantage of meshing such accounts with material records. These eyewitness accounts challenge us to rethink our models and assumptions about the adaptive strategies and coping mechanisms that the past societies used to deal with epidemical outbreaks.

Ọ̀yọ́-Ilé was evacuated in 1836, not because of the epidemic outbreaks but because of the political crises that predated and outlasted the pathogenic attacks. Unfortunately, the memory of the isolation site’s location has not survived. While Lander’s story provides no clue on how we might trace and identify this isolation center, it leaves us with many questions. What would the site look like today in the archaeological landscape? Was this the only isolation site for managing infectious diseases in the history of Ọ̀yọ́-Ilé? Was it even the only one established to contain the epidemics of 1827–1831? How do we go about detecting such sites in the archaeological record, especially around the perimeters of the city?

Sacred groves were integral parts of most of the Yorùbá towns and cities that survived until the 1950s. Some neighborhoods within these urban centers even had their designated sacred groves. Only a few have survived until today. These groves are important religious sites and are the focal points for commemorating ancestral legacies and renewing communal solidarity. I have found them indispensable for answering questions about community sociogenesis (Ogundiran 2002, 2014; Ogundiran and Ogunfolakan 2017). In the past, those who suffered from unknown ailments, especially contagions, were also brought to some of these groves, similar to the process of isolation that Richard Lander documented in Ọ̀yọ́-Ilé in 1827. In addition, they were the sites where those who died of unusual circumstances, such as deceased pregnant women, were buried.

The indigenous Yorùbá urbanism has been a topical subject in anthropology and cultural geography since the 1960s (e.g., Bascom 1969; Mabogunje 1967; Wheatley 1970). The status of cities and towns as the core of Yoruba sociopolitical organization seems to predate the eleventh century. The largest of these early urban centers was Ilé-Ifẹ̀, a name that means “house of abundance.” It was an emporium, an industrial center, a pilgrim city, and the capital of an empire ca. 1000–1420, during the Yoruba classic period (Ogundiran 2020). At its height, in the mid-fourteenth century, Ilé-Ifẹ̀ was a vast metropolis comprising of a 5-km wide city, a sprawling suburb of 5–7 km in radius, and an estimated population of about 70,000–105,000 people (Kusimba et al. 2006).

The oral traditions and embodied ritual practices of Ilé-Ifẹ̀ indicate that two episodes of epidemic outbreaks bracketed the city’s classical period. The first was associated with the conflict between two factional groups—Ọbàtálá and Odùduwà—who fought over the control of the nascent city sometime in the late tenth or early eleventh century. The stalemate between the two ended when a bout of pox epidemic, possibly a Variola (smallpox) outbreak, ravaged the stronghold of the Ọbàtálá faction. Weakened and decimated, the group was forced to arrange for a truce with the opposition—the Odùduwà group. The annual Ìtàpá festival in present-day Ilé-Ifẹ̀ commemorates the end of that conflict and the reconciliation that followed. Ìtàpá also memorializes the pox outbreak, as evident in the imagery of smallpox lesions painted on the bodies of Ọbàtálá priests with white chalk during the festival (Olupona 2011; Fig. 2). The festival is a memory work of about a thousand years.

Fig. 2
figure 2

Bodily representation of smallpox epidemic during the annual Ìtàpá festival in Ilé-Ifẹ̀

The second epidemic event happened in the last decades of the fourteenth century. The city was suffering from economic recessions at that time. Regional sociopolitical instabilities as far as Western Sudan had contracted Ilé-Ifẹ́’s long-distance commerce—the basis of its economic and political dominance. On top of this, recurrent episodes of drought worsened the floundering economy of the city. Local historians tell us that what was once a city of abundance became a land of scarcity (Horton 1992, p. 135). Conflict, high mortality rate, and emigration depleted the city’s population. Similar to what happened in Ọ̀yọ́-Ilé in 1827–1831, epidemic outbreaks were part of these cascading perturbations. The archaeological research in Ilé-Ifẹ̀ has not captured any of these details. The stratigraphies of memory rather than of sediments are our only guide to these critical aspects of the past. However, both archaeological and historical research indicates that Ilé-Ifẹ̀ experienced population decline in the late fourteenth through the mid-fifteenth century. The local memory and cultural archives of Ilé-Ifẹ̀ provide the framework that we can use to explore the multidimensional reasons for the decline. And, if the metaphor of “collapse” is our preference for interrogating that decline, we must be specific about what collapsed—demography or society; these are two different things.

The smallpox epidemic had been part of Yorùbá urban history for more than a thousand years, as the Ìtàpá rituals in Ilé-Ifẹ̀ indicate. Until its eradication in the twentieth century, no disease was as dreadful as smallpox among the Yorùbá in terms of its high rate of infection, propensity to spread and kill swiftly, and unpredictable reoccurrences. The seasonality of its prevalence, the height of the dry season (January–February), also made it an opportunistic killer. That is, it attacked its victims at the time they were most vulnerable—low food, low energy, and low level of immunity. Smallpox is feared for its indiscriminate attack, killing both the rich and the poor, and the disease is deified. Named Ṣọ̀npọ̀nná, the deity has the appellation, “king of kings,” and many nicknames, including Ọbalúayé, “the king who is lord of the world” and Babalúayé, “the father who is the lord of the earth” (Idowu 1994 (1962), p. 99–101). The priests of Ṣọ̀npọ̀nná presided over the management of the infectious disease. These priests did more than make sacrifices and pray to the deity. They were the medical specialists for preventing and treating smallpox. They immunized people through inoculation, provided medical care for the sick, and conducted burial for those who died from the disease. These priests were revered but also feared for their knowledge. After all, they had the know-how to contain and unleash the virus (Adeoti and Imuoh 2016).

Urbanism is a popular subject in archaeology. Cities and towns are one of the hallmarks of social complexity, as centers of innovation, wealth accumulation, commerce, and both vertical and horizontal differences (e.g., Monroe 2018). But urban centers are also combustion sites for epidemic outbreaks as we have already seen all over the world with the COVID-19 pandemic. Ironically, the type of settlement culture that the Yorùbá preferred was also the one that pathogens favored. The ancestral Yorùbá did not dismantle their cities to go live in dispersed communities due to the fear of epidemics. Rather, they integrated isolation mechanisms into their city planning. Some of the spaces we now call sacred groves served these isolation purposes. Embedded in virtually all precolonial Yorùbá cities and towns, these groves played essential roles in the management of crises such as epidemic outbreaks. Hence, the Yorùbá aphorism, igbó nà ń gbẹ́lẹ́fọ̀n rè: “the bush is the home of a pox-afflicted person,” refers to the use of isolation practices for dealing with the outbreaks of infectious diseases (Ogundiran 2020, p. 156). Some of these bushes refer to sacred groves similar to what Richard Lander reported in Ọ̀yọ́-Ilé in 1827 (Lander 1830). Several of these have been excavated in Ilé-Ifẹ̀, Òṣogbo, Ọ̀wọ̀, and Ìlàrè, among others (e.g., Eyo 1976; Ogundiran 2014; Ogundiran and Ogunfolakan 2017).

We stand to gain a lot of insights from studying how sacred groves served as isolation centers for managing epidemical outbreaks in Yorùbá towns and cities. Who brought the infected to these groves? What protection gears did they wear? Is it possible that the pààkàrà, a branch of the Yorùbá masquerading (égúngún) tradition, played a role in the challenging task of evacuating the sick and carrying them into the sacred groves (isolation sites)? Literally, pààkàrà means “roam about.” Young men, usually of the underclass, were associated with the pààkàrà masquerades. These were the kinds of individuals who would have been recruited for moving the sick from their homes to the groves. They also possibly delivered food, water, and medicine to the sick people in these isolation centers. Unlike the ancestral masquerades, the pààkàrà costume is not voluminous and flamboyant but covers the entire body like the other égúngún.

Sacred groves are not the only place to look for the spatiality of epidemic disease management in Yorùbá towns and cities. The city perimeter walls served defensive purposes against seen and unseen enemies (including malignant microbes) and were used for controlling the movement of people. Their gates gave and denied access to those wishing to exit or enter the city. For sure, they were important sources of the state revenues in the form of the levies collected from visitors and citizens passing the gates. However, during the times of epidemic outbreaks, these gates became part of the strategy for controlling the spread of infection.

The human tolls of COVID-19 pandemic and its social, political, economic, and psychological impacts have raised questions and stimulated new thinking on how ancient African communities managed microbial invasions. The ancestral Yorùbá maintained their cheek by jowl urban residential patterns for more than ten centuries despite the periodic outbreaks of epidemics like smallpox and infectious respiratory diseases. We need to pay attention to their settlement landscape and the social ecology of their urbanism to understand how they achieved that feat. We should also be attentive to their stratigraphies of memory and cultural archives. These tell us that the ancestral Yorùbá were aware of some aspects of the germ theory of disease before these were widely accepted in Western science during the nineteenth century. Like many other West African peoples, they practiced inoculation to build immunity against smallpox (Holloway 2005, p. 39). During epidemic outbreaks, they used “sacred groves” to isolate the sick from the healthy. And, in extreme cases, whole compounds were abandoned or burnt to slow down infection rate. With these preventive, proactive, and defensive strategies, the ancestral Yorùbá urban culture survived many of those cycles of microbial attacks for about a thousand years.