In this episode, Lucas and Luna explore the collapse of the Mongol Empire's legendary Yam network — the vast postal relay system that once stretched from the Black Sea to the Pacific. They trace how the Yam, originally created by Ögedei Khan and perfected by Möngke, became a weapon of internal strife. As the empire fractured into warring khanates, post stations were seized by local lords, tolls skyrocketed, and merchants were robbed by the very riders meant to protect them. The hosts focus on a single ruinous year — 1262 — when Berke and Hulegu's war severed the Yam across Central Asia, isolating Karakorum from the Ilkhanate and the Golden Horde. They also examine the little-known role of the darughachi, Mongol overseers who abused the system for personal gain, and the failed reform attempts by Khubilai Khan in the east and Ghazan Khan in the west. The episode argues that the Yam's disintegration wasn't just a symptom of the empire's breakup — it was a cause, because without fast communication, no central authority could hold. Featuring the perspectives of the Persian historian Juvayni, who managed the Yam in Iraq, and the Venetian merchant Marco Polo, who travelled its decaying remnants.