Plague burials at Kara-Djigach in the Chüy valley

The cemeteries of Kara-Djigach, on the outskirts of present-day Bishkek, some 125 km from Lake Issyk-Kul, and Burana, both in the Chüy valley of Kyrgyzstan, belonged to communities of the Church of the East whose tombstones are inscribed in Syriac and Turkic; their people traded along the routes crossing Central Asia and kept ties across Eurasia. Excavated between 1885 and 1892, the cemeteries yielded hundreds of tombstones, published by the orientalist D. A. Chwolson. Of 467 dated stones, a disproportionately large number belong to 1338 and 1339, and some inscriptions state that the deceased died of ‘pestilence’ (Syriac mawtānā) — like the tomb of ‘the believer Sanmaq’, dated to the Year of the Tiger, 1338.

For more than a century scholars argued whether this local epidemic was plague and whether it had anything to do with the Black Death; John Norris (1977) saw in it only a small sporadic outbreak and looked for the origin of the pandemic further west. In 2022 a team led by Maria Spyrou, Philip Slavin and Johannes Krause published ancient DNA from the teeth of seven people buried in the two cemeteries — ‘near Lake Issyk-Kul’, as the authors put it — and kept in the Kunstkamera in St Petersburg. Three individuals from Kara-Djigach, all buried in 1338–1339, carried Yersinia pestis; two reconstructed genomes represent a single strain, which the authors identify, at the resolution of their data, as the direct ancestor of the great diversification of plague lineages (the ‘polytomy’ of branches 1–4) that produced the strains of the Black Death and most of the modern strains in their sample. Its closest living relatives are found in plague foci of the wider Tian Shan, mostly among marmots; the authors consider this consistent with a local emergence of the strain, though they cannot rule out that these lineages once lived elsewhere, and date the diversification to the first half of the 14th century.

Outbreaks around the Black Sea in 1346 came eight years after the Kara-Djigach epidemic. How the bacterium travelled west is still unknown: the authors note that the Chüy valley lay close to the trans-Asian trade networks, which supports a role for trade, but their narrow sampling cannot show how the strain spread.