The outbreak of the Third Plague Pandemic in the Yunnan province in China, and early spread

In the 1860s, missionaries and explorers reported from the Yunnan province in China that ‘true’ plague was observed there. The ensuing events that triggered the Third Plague Pandemic have often been misrepresented and allegedly showed that this plague had highly different properties from the Black Death and the Second Plague Pandemic. It is claimed, among other things, that the spread rates were highly different. For this reason, the events will be presented in some more detail than otherwise would have been necessary in a book on the Black Death. Because, as paleobiologists have shown, the lineage of plague bacteria in Yunnan was closely genetically related to the plague contagion of the Black Death and the Second Plague Pandemic, the disparity of properties would be hard to explain also for this reason (see below).

Yunnan was a remote western province on the border of Burma and near to Tibet and Vietnam. It was ‘isolated by its position and its physical features, [and] had only a limited intercourse with its neighbours and with treaty ports’. The main export products were tin and opium. Plague in Yunnan is not mentioned in Chinese sources before 1792. Probably, it was not of long standing but connected with an offshoot of the Second Plague Pandemic in Europe, which is mentioned in Chinese sources in the early 1640s. It was, in fact, a genuine descendant of the Black Death that had struck roots in the Yunnan province.

The crucial event was a sudden upsurge of military activity in response to a Muslim rebellion that broke out in 1855 and entailed a strongly increased traffic of movement of troops, provisions and refugees, and with it the incidence of movement of plague contagion. In 1866, the provincial capital was ravaged by a severe plague epidemic ‘in the midst of war’. The following year, returning troops transported plague a long and difficult journey of 1,600 km to the burgeoning coastal commercial hub of Pakhoi on the eastern coast of the Tonkin Gulf, and a serious plague epidemic broke out.