The study of the Black Death exploded around the time of the outbreak of COVID-19. That was due no doubt in part to widespread renewed interest in pandemic disease, though it also drew on significant recent genomic work on plague, particularly the idea of a ‘polytomy,’ a moment of divergence of major plague strains, which Cui et al. (2012) located on the Qinghai-Tibet Plateau. For more than a generation, the standard treatments of the Black Death were the 1976 Plagues and Peoples, by William McNeill and the 1977 The Black Death in the Middle East, by Michael Dols. The new wave of work was signaled by a series publications several years before the outbreak of COVID-19. In 2014, Monica Green edited the inaugural special issue of The Medieval Globe as a collection of articles ‘rethinking the Black Death.’ This included a ‘hypothesis’ by Robert Hymes about the spread of the plague from the Qinghau-Tibet Plateau into north China on the heels of the Mongol invasion of Xia and beyond. This journal volume was then published in book form in 2015. That same year saw Nükhet Varlık’s award-winning book on the spread of the plague in the early modern Mediterranean, which was followed by several other volumes written or edited by Varlık.
For the Mongol lands and period specifically, an important touchstone was Monica Green’s 2020 article, ‘The four black deaths,’ and a second article published the following year by Green and Nahyan Fancy, ‘Plague and the fall of Baghdad.’ These made the case for Mongol involvement in the transmission of plague from Central Asian reservoirs to Southwest Asia already in the thirteenth century. This was facilitated, in Green’s view, by the Mongol army’s practice of transporting and stockpiling grain, particularly for prolonged sieges, which naturally meant also the transmission of large numbers of rodents. The 2021 article by Green and Fancy reexamined textual evidence for the outbreak of disease during and after the Mongol siege of Baghdad, arguing that the diversity of terms used might in fact conceal an outbreak of a localized endemic plague reservoir that the witnesses didn’t yet know how to identify.
Unfortunately, the line of argumentation hypothesized by Hymes and developed by Green and Fancy was not allowed to develop along its normal lines, since in 2022 a high-profile article was published in Nature (Spyrou et al.) about genetic material from Yersinia pestis found in a series of tombs from Khara Djigach, near Issyk Kul in northern Kyrgyzstan. The genetic results suggested that this local outbreak closely preceded the great polytomy of plague strains. Notably, these tombs had tombstones and many mentioned pestilence, indicating a major spike in plague mortality in 1338–9, just a few years before the better-documented epidemic in Europe. Based on this evidence, several scholars, most notably Philip Slavin, has developed the idea that the polytomy of plague post-dated the deaths at Kara Djigach, and may even have occurred in conjunction with the 1338–9 Issyk Kul outbreak.
Slavin pairs the Kara Djigach genetic material with paleoclimactic data and evidence of widespread de-urbanisation in Central Asia to argue for a rapid fourteenth-century explosion of plague from there across western Eurasia and into Europe. This ‘quick transit theory’ is in contrast to the ‘localised’ model of Green and Fancy, which sees earlier introduction of plague into Southwest Asia, from where it broke out in the context of hardship that accompanied the Mongol conquests.
Many continue to see the Kara Djigach evidence as a smoking gun for a late polytomy and a fast spread. Perhaps the most stringent example of this is the 2024 article of Brack et al., which seeks to rebut Green and Fancy’s work on sources around the siege of Baghdad. This ‘reevaluation’ brings the skills of three formidable philologists to the debate to conclude that the evidence does not conclusively point to plague, but that the disease outbreaks mentioned in the sources were probably a diversity of infections that took hold under the stress of siege. However, the article also rests great faith in the Kara Djigach hypothesis of Spyrou et al. as proof positive of a fourteenth-century westward spread of the Black Death.
In a response published in 2024, Green and Fancy point out that Brack et al. do not directly engage with their idea of plague focalisation. Furthermore, they show how Spyrou et al. is not a definitive result, but has been assumed as such by historians putting too much faith in scientific data. Specifically, they show that full-genome testing of Yersinia pestis aDNA (ancient DNA) yields different results than the single nucleotide polymorphism (SNP) variations used for the 2022 Nature article. Indeed, they show (figure 2B) that according to full-genome testing phylogeny, the Kara Djiagach samples significantly postdate the great polytomy, reopening the question of where and when the extant main lines of plague diverged from one another.
Green and Fancy furthermore argue for looking at indirect evidence of things known from other contexts to co-occur with plague, including possible causes like climate changes and expected human reactions such as economic decline or religious and supernatural responses. These, notably, are exactly the kinds of evidence on which Slavin draws to make his broader argument about the reasons for rapid and massive deurbanization in Central Asia. The crux of the disagreement between them seems to come down to three main issues: the type of genetic markers used to create the phylogeny of plague, the location and dating of the great polytomy of plague, and ideas about the speed and nature of its spread after that event.
Bibliography (most significant titles only)
Jonathan Brack, Michal Biran, and Reuven Amitai, “Plague and the Mongol Conquest of Baghdad (1258)? A Reevaluation of the Sources,” Medical History, https://doi.org/10.1017/mdh.2023.38
Cui et al., ‘Historical Variations in Mutation Rate in an Epidemic Pathogen, Yersinia pestis,” Proceedings of the National Academy of Science 110, no. 2 (27 Dec 2012), 577–582.
Fancy, Nahyan, and Monica H. Green. “Plague and the Fall of Baghdad (1258),” Medical History 65, no. 2 (April 2021), 157-17.
Green, Monica H. (ed.), Pandemic Disease in the Medieval World: Rethinking the Black Death, inaugural issue of The Medieval Globe 1, no. 1-2 (Fall 2014), 9-26; repr. as Pandemic Disease in the Medieval World: Rethinking the Black Death, ed. Monica H. Green (Amsterdam and Kalamazoo, MI: Arc-Medieval Press, 2015).
Green, Monica H. “The Four Black Deaths,” American Historical Review 125, no. 5 (December 2020), 1600-1631. https://doi.org/10.17613/7020-8j08
Green, Monica H., and Nahyan Fancy. “Plague History, Mongol History, and the Processes of Focalisation Leading up to the Black Death: A Response to Brack et al.,” Medical History 68, no. 4 (Fall 2024), 411-435. https://doi.org/10.1017/mdh.2024.29
Slavin, Philip. “The Birth of the Black Death: Biology, Climate, Environment, and the Beginnings of the Second Plague Pandemic in Early Fourteenth-Century Central Asia,” Environmental History 28, no. 2 (April 2023), 300–334, published online 23 March 2023.
Spyrou, Maria A., et al. “The Source of the Black Death in Fourteenth-Century Central Eurasia,” Nature 606 (23 June 2022), 718–724
Varlık, Nükhet. Plague and Empire in the Early Modern Mediterranean World: The Ottoman Experience, 1347–1600(Cambridge, UK: Cambridge University Press, 2015)
Note also that Monica Green has been managing a public bibliography of plague studies since 2020. It is currently over 204 pages long, and his highly structured, with indexing and internal cross-reference: https://docs.google.com/document/d/1x0D_dwyAwp9xi9sMCW5UvpGfEVH5J2ZA/edit