Any benefits derived from participation in Mongol networks of communication and exchange must be measured alongside the hemispheric catastrophe known as the “plague” or the “pestilence” and later called the Black Death. Originating most likely in China, the bacteria responsible for the disease, known as Yersinia pestis, spread across the trade routes of the vast Mongol Empire in the early fourteenth century (see Map 11.2). Carried by rodents and transmitted by fleas to humans, the plague erupted initially in 1331 in northeastern China and had reached the Middle East and Western Europe by 1347. One lurid but quite uncertain story has the Mongols using catapults to hurl corpses infected with the plague into the Genoese city of Caffa in the Crimea. In 1409, the plague reached East Africa, probably by way of the famous Chinese maritime expeditions that encompassed the Indian Ocean basin.

The disease itself was associated with swelling of the lymph nodes, most often in the groin; terrible headaches; high fever; and internal bleeding just below the skin. Infected people generally died within a few days. In the densely populated civilizations of China, the Islamic world, and Europe as well as in the steppe lands of the nomads, the plague claimed enormous numbers of human victims, causing a sharp contraction in Eurasian population for a century or more. Chroniclers reported rates of death that ranged from 50 to 90 percent of the affected population, depending on the time and place. A recent study suggests that about half of Europe’s people perished during the initial outbreak of 1348–1350.30 A fifteenth-century Egyptian historian wrote that within a month of the plague’s arrival in 1349, “Cairo had become an abandoned desert. . . . Everywhere one heard lamentations and one could not pass by any house without being overwhelmed by the howling.”31 The Middle East generally had lost perhaps one-third of its population by the early fifteenth century.32 The intense first wave of the plague was followed by periodic visitations over the next several centuries, although India and sub-Saharan Africa were much less affected than other regions of the Eastern Hemisphere.

But in those places where it struck, the plague left thoughtful people grasping for language with which to describe a horror of such unprecedented dimensions. One Italian man, who had buried all five of his children with his own hands, wrote in 1348 that “so many have died that everyone believes it is the end of the world.”33 Another Italian, the Renaissance scholar Francesco Petrarch, was equally stunned by the impact of the Black Death; he wrote to a friend in 1349:

In the Islamic world, the famous historian Ibn Khaldun, who had lost both of his parents to the plague, also wrote about it in apocalyptic terms:

(See Visual Sources: The Black Death and Religion in Western Europe for more on religious response to the plague in Europe.)

Beyond its immediate devastation, the Black Death worked longer-term changes in European society, the region where the plague’s impact has been most thoroughly studied. Labor shortages following the initial outburst provoked sharp conflict between scarce workers, who sought higher wages or better conditions, and the rich, who resisted those demands. A series of peasant revolts in the fourteenth century reflected this tension, which also undermined the practice of serfdom. That labor shortage also may have fostered a greater interest in technological innovation and created, at least for a time, more employment opportunities for women. Thus a resilient European civilization survived a cataclysm that had the power to destroy it. In a strange way, that catastrophe may have actually fostered its future growth.

Whatever its impact in particular places, the plague also had larger consequences. Ironically, that human disaster, born of the Mongol network, was a primary reason for the demise of that network in the fourteenth and fifteenth centuries. Population contracted, cities declined, and the volume of trade diminished all across the Mongol world. By 1350, the Mongol Empire itself was in disarray, and within a century the Mongols had lost control of Chinese, Persian, and Russian civilizations. The Central Asian trade route, so critical to the entire Afro-Eurasian world economy, largely closed.

This disruption of the Mongol-based land routes to the east, coupled with a desire to avoid Muslim intermediaries, provided incentives for Europeans to take to the sea in their continuing efforts to reach the riches of Asia. Their naval technology gave them military advantages on the seas, much as the Mongols’ skill with the bow and their mobility on horseback gave these nomads a decisive edge in land battles. As Europeans penetrated Asian and Atlantic waters in the sixteenth century, they took on, in some ways, the role of the Mongols in organizing and fostering world trade and in creating a network of communication and exchange over an even larger area. Like the Mongols, Europeans were people on the periphery of the major established civilizations; they too were economically less developed in comparison to Chinese and Islamic civilizations; both were prone to forcibly plundering the wealthier civilizations they encountered; and European empire-building in the Americas, like that of the Mongols in Eurasia, brought devastating disease and catastrophic population decline in its wake.36 Europeans, of course, brought far more of their own culture and many more of their own people to the societies they conquered, as Christianity, European languages, settler societies, and western science and technology took root within their empires. Although their imperial presence lasted far longer and operated on a much larger scale, European actions at the beginning of their global expansion bore some resemblance to those of their Mongol predecessors. They were, as one historian put it, “the Mongols of the seas.”37