One empire across the routes

In the thirteenth century something happened that had never happened before: a single dynasty came to rule almost the whole overland network. The Mongol conquests, which began under Chinggis Khan in 1206, were extraordinarily destructive. Cities that resisted, such as Merv and Nishapur, were sacked and their people killed or deported, and skilled artisans were often moved across Asia by force to serve their new masters. Any account of the Mongol era that leaves out that violence is a whitewash.

Yet once the conquests were complete, the Mongol rulers had strong reasons to encourage trade, which they taxed, and travel, which bound their realm together. Historians sometimes call the period from about 1250 to 1350 the Pax Mongolica, the Mongol peace. Even after the empire split into four rival khanates in the 1260s, merchants and envoys moved more easily across Eurasia than at any time before.

Roads, passes and protection

Two institutions made this possible. The yam was a relay system of post stations, spaced along major roads, where official messengers and envoys could get fresh horses, food and lodging. Riders carrying urgent news could cover remarkable distances in a day. Travelers on official business carried a paiza, a metal tablet granting its holder official protection and the right to use the stations. Merchants partnered with Mongol nobles, who lent them capital and expected a share of profits, so commerce and power were tightly linked.

Travelers in both directions

The new conditions drew travelers who left vivid records. The Flemish friar William of Rubruck, sent by the French king Louis IX, journeyed to the Mongol capital Karakorum from 1253 to 1255. There, in 1254, he took part in a debate among rival faiths, staged at the court of the Great Khan Möngke, in which Christians, Muslims and Buddhists argued about God before judges. Rubruck reports that at the end the participants drank heavily and no one converted.

Travel also ran from east to west. Rabban Sauma, a monk of the Church of the East born near modern Beijing, set out on pilgrimage for Jerusalem and ended up as a diplomat. In 1287 the Mongol ruler of Iran, Arghun, sent him to Europe to seek allies against the Mamluks of Egypt, the Mongols' great enemy in the Middle East. He met Philip IV of France and Edward I of England, and the newly elected pope in Rome. No alliance followed, but his account offers a rare view of medieval Europe through Asian eyes. Marco Polo and Ibn Battuta, whose travels are better known, belong to the same world of Mongol era movement.

A merchant's handbook

Around 1340 a Florentine banker's agent, Francesco Balducci Pegolotti, compiled a handbook of practical commerce. It includes directions for traveling from Tana, a port on the Sea of Azov, to China, which Europeans called Cathay. Pegolotti advised merchants to grow beards, hire good interpreters and take enough provisions, and he reported that merchants who had used the road called it safe. In a nineteenth century translation: "The road you travel from Tana to Cathay is perfectly safe, whether by day or by night, according to what the merchants say who have used it." He added a warning that if a ruler died, the road could become dangerous until a successor took power.

The roads carry death

The same connections spread disease. The great plague of the 1340s, the Black Death, killed vast numbers in Asia, the Middle East and Europe. Where did it begin? A study published in 2022 analyzed DNA from skeletons in cemeteries in the Chu Valley of Kyrgyzstan, where gravestones from 1338 and 1339 mention death from pestilence. The researchers found an early plague strain in graves from 1338, ancestral to the strains that later swept west, which points to Central Asia as the origin.

A famous story says the plague reached Europe when a Mongol army besieging the Genoese port of Caffa, in Crimea, in 1346 catapulted infected corpses over the walls. The source is the Italian lawyer Gabriele de' Mussis. Historians are cautious, because he was probably in Italy, not at Caffa, and fleeing ships and infected rats and fleas would have spread the disease anyway. The plague, together with the breakup of the khanates and the fall of the Mongol Yuan dynasty in China in 1368, ended the Mongol peace.

Worked example: reading Pegolotti

Pegolotti's handbook looks like proof that the Mongol roads were safe. Read it closely. First, note his source: he did not travel the route himself, as far as we know; he reports "what the merchants say". That is valuable, since it reflects many traders' experience, but it is hearsay. Second, note his caveat about a ruler's death. Safety depended on political stability, not on law or rights that merchants could claim. Third, note his practical tips: beards, interpreters, provisions. These suggest a route used often enough to have standard advice.

So the handbook supports a qualified conclusion: for a few decades the route was regular and reasonably secure, under the protection of a power that had won it through slaughter, and that security could vanish overnight. Within a decade of Pegolotti's writing, the plague had swept along the very roads he described.