Many foreign visitors, including Marco Polo himself, were in awe of Yam’s size and reliability. It was a vast collection of postal stations, with dedicated messengers delivering mail, intelligence reports, and important news from station to station. These stations were about 24–64 kilometers (15–40 mi) apart, and were kept constantly staffed. At one point, there were at least 1,400 stations in China alone, and the messengers had 50,000 fresh horses at their disposal.
