Essential to controlling the vast Mongol Empire was a robust and hyper communications network. History has enshrined the medieval Mongol horse-archer as one of the greatest military units of all time, but the Mongol horseback messengers have not been given such renown–though they certainly deserve it so. During the Mongol Yuan Dynasty’s reign over Asia, news from distant lands could travel ten times faster than previously possible because of the Mongol postal system, or the “horse-post-house” yam system.

The Yam

A yam was a waystation where a “large and handsome building” housed messengers and horses in “rooms furnished with fine beds” fit for a king, decorated with “rich silk” and “everything they can want.” (Polo, 434). Yams were set up at intervals of 25 to 45 miles along major highways, country roads, and empty swathes of land between provinces. Any news of governmental importance, such as the uprising of a rebellion, could reach the Mongol Emperor in intimidatingly fast time.

Depending on the size and business of the yam, there could be 200 to 400 horses on the ready for the messengers to ride. The speedy operation of this postal service depended on these horses. A messenger would ride a horse as hard as possible to reach the next yam as fast as possible. They rode so intensely that they had to tie themselves to the horse with tight bands around their head, chest, and stomachs to prevent themselves from falling off. At night, their speed would be reduced as a torch would have to be carried to guide the way. Nonetheless, accounts from that era say that a distance of 200-250 miles could be covered in a single day this way. (Polo, 435).

A vast livery allowed fresh horses to always be available.  These horses were recruited by a taxation system in which, “Every city, or village, or hamlet, that stands near one of those post-stations, has a fixed demand made on it for as many horses as it can supply.” (Polo, 435). And if a messenger’s horse should ever fail on the road, the messenger was equipped with a government seal enabling him to seize any person’s horse. Such was the importance placed on this postal system.

At each yam, a clerk marked down the time of the messenger’s arrival and the time of the subsequent messenger’s departure in order to track down and eliminate any lags or inefficiencies. If the message or delivery was urgent, then the messenger wore a belt of bells in order to alert the yam to prepare a new horse and messenger posthaste. 

The Network

By the end of the 13th century C.E., more than 300,000 horses and 10,000 yam post offices were in operation throughout Asia. This according to the accounts of Marco Polo, who served in the administration of Emperor Kublai Khan’s Mongol Yuan Dynasty.

Just as well, foot-runners were stationed at smaller posts every 3 miles. These couriers would take their turns sprinting at full speed for the 3 miles to the next post where the next runner would take the message and run it over to the next post. And anywhere crossed by a river or lake, a fleet of small boats would similarly be kept on the ready.

This system allowed the expedited delivery of goods and messages. For example, a piece of fruit could be harvested one morning in Cambaluc (modern: Beijing, China) and by that evening arrive in Xanadu (modern: Shangdu Town, Inner Mongolia, China), a distance of 220 miles, for the Emperor to enjoy. What would typically be a 10-day journey became a 1-day trip, and a 100-day journey became a 10-day trip under the Mongol horse-post-house, yam, or pony-express type system.

The Historical Impact

This post system was introduced to Genghis Khan by the Chinese Song Dynasty. It was expanded by his third son, Okkodai or Ögedei Khan around 1234 C.E. (Polo, 437, note 2) and utilized by Kublai Khan and his successors. But the Mongols were not unique in their use of it. Similar post systems were used in China in the 9th century by the Tang Dynasty and as far back as the Han Dynasty around the dawn of the Common Era (Richter, 168), as well as in Ancient Persia and Medieval India (Polo, 438). And the system was continued in Tsarist Russia after the fall of the Mongol Golden Horde. However, the Mongols were unique in the scale of their postal system for it covered the expanse of one of humanity’s largest empires and did so most expeditiously. For context, some few hundred years later in the 19th century, the Ottoman Empire used a nearly identical system of horse-post-houses. A message then could be delivered “from Constantinople to Baghdad, a distance of 1100 miles, in twenty days by four Tartars riding night and day…” with posts at “Sivas, Diyabakir, and Mosul.” This, at a rate of 55 miles a day, was four times slower than the 13th century Imperial Mongol system. (Polo, 438, note 7).

Maintaining an empire requires power. Just as well as military might, the importance of a good postal system is key because, after all, information is power. The Mongols learned this and put their skill on horseback to great use outside of battle as well, enabling them to maintain governance over the lands they conquered.

Sources:

• Polo, Marco, Yule, Cordier. The Travels of Marco Polo. Dover Publications, 1993, 433-438.
• Richter, Antje. Letters and Epistolary Culture in Early Medieval China (MLI / A China Program.. University of Washington Press, 2013, 155-196.
• Silverstein, Adam J. Postal Systems in the Pre-Modern Islamic World. Cambridge University Press, 2010, 141-164.