How did the yam postal network help the Mongol Empire communicate across long distances?

The yam was an extensive network of postal and supply stations established by the Mongol Empire along major trade routes to facilitate rapid communication and administration across its vast territories.12

By maintaining these stations, the Mongols enabled official couriers to travel with remarkable speed. Couriers carrying an imperial passport, known as a paiza (or geregee), were authorized to exchange their horses at these relay points, ensuring that messages and travelers could move efficiently across the empire. This infrastructure was a key component of the Pax Mongolica, as it provided the necessary connectivity to manage the largest contiguous land empire in history, supporting not only administrative communication but also the movement of diplomats and merchants across Eurasia.21