The Mongol postal relay system was called the yam, or jam. It linked relay stations across the empire, allowing official messengers to change horses, obtain food, and continue journeys at extraordinary speed.
Ögedei Khan greatly expanded and organized the yam during the 13th century. Stations were placed along major routes and supported by local populations. Messengers carried official orders, intelligence, and military reports; the network was therefore much more than a simple courier service. It was a logistical system that helped coordinate an empire stretching across much of Eurasia.
The yam is sometimes confused with the Silk Road, but the two served different purposes. The Silk Road was a broad network of commercial routes, while the yam was an administratively managed relay system. “Pony Express” is also a tempting comparison, but that was a much later American service. The system survived in parts of the former Mongol world, including Russia, after the empire fragmented.