The Black Death's Origins and Devastating Spread

Key Insight

The Black Death, or bubonic plague, originated in Southern China and was carried northward by Mongol warriors. The disease-carrying bacterium resided in fleas, which were transported on rats within food and tribute shipments. Although generally avoiding humans, these infected fleas could survive in various human-proximate environments like grain sacks and clothing. Upon reaching the Gobi, the fleas found new hosts in marmot burrows and extensive rodent colonies, where the plague has persisted, causing a handful of annual summer deaths even today. However, in the densely populated urban centers of China, and later in other cities, the plague found ideal conditions due to close human-rat proximity, leading to its rapid escalation into an epidemic. The plague manifested with severe symptoms, progressing from a healthy appearance to hot fever, chills, vomiting, and diarrhea. Victims' bodies would rapidly deteriorate, with blood oozing beneath the skin, causing discoloration, and the formation of blood and pus-filled lumps called buboes, typically in the groin, armpit, and neck, giving the disease its medical name.

As the buboes grew, they would burst open. A lack of oxygen and dried blood beneath the skin caused victims to appear black, a dramatic symptom that led to the disease's common name: the Black Death. After a few agonizing days, death usually followed. In some cases, the disease attacked the lungs instead of lymph nodes, causing victims to drown as their lungs filled with bloody, frothy air. These individuals could then infect others through violent coughing, sneezing, and gasping. The plague's devastating impact on China was recorded early, with chroniclers noting a 90 percent death rate in Hopei Province by 1331. By 1351, China had reportedly lost between one-half and two-thirds of its population, dropping from approximately 123000000 inhabitants at the beginning of the thirteenth century to as low as 65000000 by the end of the fourteenth century.

Functioning as the manufacturing hub of the Mongol World System, China inadvertently facilitated the plague's global spread. Goods exported from China carried the disease in all directions. Archaeological evidence from graves near trading posts shows that by 1338, the plague had crossed the Tian Shan Mountains from China, annihilating a Christian trading community near Lake Issyk Kul in Kyrgyzstan. The Mongol-established roads and caravan way stations, initially designed for merchants to move silk, spices, and other luxury goods, became crucial inadvertent transfer points for the infected fleas. Caravans, laden with valuable commodities, thus became vectors, spreading the plague from camp to camp, village to village, city to city, and ultimately, continent to continent. This 'epidemic of commerce' reached Sarai, the capital of the Golden Horde on the lower Volga, in 1345. Although a story persists of Yanibeg, the Kipchak khan, catapulting plague victims' bodies into the besieged Crimean port of Kaffa in 1345, this account from Gabriele de Mussis, who claimed to have heard it from sailors, is considered doubtful because dead bodies alone would not effectively transmit the disease; living fleas would be necessary. Regardless of intent, refugees and merchants fleeing Kaffa by boat carried the disease to Constantinople, from where it quickly spread to Cairo in Egypt and Messina in Sicily. Ships, with their enclosed environments, proved ideal incubators for humans, rats, and fleas to mix intimately without the repellent presence of horses or fire. Freed from the slower pace of land routes, the plague then spread with remarkable speed, ravaging Italian cities in 1348, reaching England by June of that year, and crossing the North Atlantic to the Faeroe Islands, Iceland, and Greenland by the winter of 1350. It potentially killed 60 percent of Iceland's settlers and was likely the primary factor in the extinction of the struggling Viking colony in Greenland.