The ruler of the Mongol Empire who established a system of postal relay stations was Genghis Khan. He implemented the famous Yam system, which facilitated rapid communication and transport across the vast empire. This system consisted of a series of relay stations, manned by runners or horse riders, allowing messages to cover great distances efficiently. It enhanced military coordination and administrative governance, contributing to the empire's unity and control. Genghis Khan's innovations in communication played a significant role in the Mongol Empire's expansion and effectiveness.