The yam was the postal relay system of the Mongol Empire, a network of way stations located at intervals of roughly twenty-five to thirty miles across the whole of the empire. The yam was one of the most important institutions of the Mongol state, and it was a major factor in the success of the Mongol military, the Mongol administration, and the Pax Mongolica. The system made it possible to communicate across the empire in a matter of weeks, and it was, in many ways, the medieval equivalent of the modern postal system.
The yam was modeled on similar systems that had existed in China and Persia, but it was on a much larger scale than any previous system, and it was more efficient. The system covered the entire territory of the Mongol Empire, from Korea to the Crimea and from Siberia to the Persian Gulf, and it was maintained by a large staff of officials, soldiers, and servants.
The Word “Yam”
The word “yam” (also spelled “yamma,” “jam,” or “jami”) is the Turkic-Mongolian term for “road” or “station” — it is the same word as the modern Russian yamshchik (postilion), the modern Turkish yam, and the modern Mongolian zam. It is not, despite a popular claim sometimes made, the source of the English word “Pony Express” — the Pony Express was an American private mail service of 1860–1861, named by its operators for the fast horses used. The two systems are, however, often compared by historians, and the Mongol yam is the more durable institution by several centuries.
The yam system was also known as the “örteg” in Mongolian, a term that refers to a relay station or a courier station. The system was administered by a special office of the imperial government, called the “Yam Office” or the “Postal Office,” which was responsible for the maintenance of the way stations, the breeding of the horses, and the staffing of the couriers.
The Structure of the System
The yam system was organized as a network of way stations, called “yams” or “stations,” located at intervals of roughly twenty-five to thirty miles along the major routes of the empire. The yams were established at strategic points, typically near a source of water and pasture, and they were equipped with a supply of fresh horses, a supply of food and lodging, and a staff of officials, soldiers, and servants.
The yams were administered by a special office of the imperial government, the “Yam Office” or the “Postal Office,” which was responsible for the maintenance of the stations, the breeding of the horses, and the staffing of the couriers. The yams were staffed by a mix of Mongols, Turks, Chinese, and other peoples, and the staff was responsible for the safety of the couriers and the maintenance of the horses.
The horses used in the yam system were bred especially for the purpose, and they were typically the small, hardy breed that was characteristic of the Mongolian steppe. The horses were kept at the yams and were made available to the couriers on demand. The couriers were required to use the horses provided by the yams, and they were required to deliver their messages in a timely fashion.
The Couriers
The couriers of the yam system were the backbone of the postal system. The couriers were selected for their speed, endurance, and reliability, and they were given a special status in the imperial service. The couriers carried messages in a leather pouch, called a “gereg,” that was sealed by the sender and that could be opened only by the recipient. The gereg was the medieval equivalent of a sealed letter, and it was the basis of the security of the postal system.
The couriers were required to maintain a high speed in the delivery of their messages, and they were required to ride day and night, changing horses at each yam. The fastest couriers could cover up to 200 miles in a single day, and the most important messages could be delivered across the empire in a matter of weeks. The speed of the courier service was a major advantage for the Mongol military, and it was a major factor in the success of the Mongol campaigns.
The couriers were also required to maintain a high standard of discretion, and they were forbidden from discussing the contents of their messages with anyone. The couriers were given a special seal, the “paiza” or “gerege,” that they were required to carry with them at all times, and the seal was the basis of their authority to demand fresh horses and lodging at the yams.
The Imperial Passport (Paiza)
The imperial passport, called the “paiza” (also spelled “paizi,” “baksi,” or “gerege”), was a tablet of metal, wood, or ivory that was issued by the imperial government and that entitled the bearer to demand fresh horses, lodging, and food at the yams. The paiza was the medieval equivalent of a diplomatic passport, and it was the basis of the security of the postal system.
The paiza was issued in a number of different forms, depending on the rank of the bearer. The most elaborate paizas were made of gold and were issued to members of the imperial family; the simpler paizas were made of silver or wood and were issued to lower-ranking officials. The paiza was inscribed with the seal of the issuing authority, and it was the basis of the bearer’s authority to demand services from the yams.
The paiza was a major innovation of the Mongol administration, and it was widely copied by the successor states of the Mongol Empire. The paiza is also significant for what it tells us about the reach of the Mongol Empire: the fact that the paiza was recognized across the entire Eurasian landmass is a striking reminder of the political unity that the Mongols had achieved.
The Importance of the Yam
The yam was one of the most important institutions of the Mongol state, and it was a major factor in the success of the Mongol military, the Mongol administration, and the Pax Mongolica. The system made it possible to communicate across the empire in a matter of weeks, and it allowed the government to send orders and reinforcements to the front in a matter of weeks. The system also allowed the government to gather intelligence from the far ends of the empire, and it allowed the merchants to supply the army with goods and materials.
The yam was also a major factor in the spread of the Pax Mongolica. The system made it possible for merchants, missionaries, and other travelers to move across the empire with a degree of safety and predictability that was unmatched in the medieval world. The system was, in effect, the foundation of the commercial and cultural exchange that characterized the Mongol period, and it was one of the keys to the success of the Mongol Empire.
The Decline of the Yam
The yam system entered a long period of decline in the mid-fourteenth century. The Black Death, which swept across Eurasia in the 1340s, killed millions of people and disrupted the yams that had made the system possible. The collapse of the Ilkhanate in 1335 and the Yuan Dynasty in 1368 removed the two khanates that had been the principal guarantors of the system. The rise of the Ming Dynasty in China, the Timurid Empire in Central Asia, and the Grand Duchy of Moscow in Russia created new political configurations that were less favorable to long-distance communication.
The decline of the yam was a major turning point in the history of Eurasia. The postal system became more dangerous and less reliable, and the center of communication shifted from the interior of the continent to the maritime periphery. The age of exploration that began in the fifteenth century was, in a sense, a response to the breakdown of the yam: the European voyages of discovery were attempts to find new routes to the east that did not depend on the overland routes that had been disrupted by the collapse of the Mongol peace.
Sources
- Timothy May, The Mongol Art of War (Barnsley: Pen & Sword, 2007), ch. 7.
- David Morgan, The Mongols (2nd ed., Oxford: Blackwell, 2007), ch. 2.
- Christopher I. Beckwith, Empires of the Silk Road (Princeton: Princeton University Press, 2009), ch. 6.
- René Grousset, The Empire of the Steppes (New Brunswick: Rutgers, 1970), ch. 7.
- Christopher Dawson, ed. and trans., The Mongol Mission (New York: Sheed & Ward, 1955) — for the European eyewitness descriptions of the yam in the 1240s and 1250s.