# 【67-4】返事はまだですか？返事は？モンゴルからの国書と日本の判断【COTEN RADIO モンゴル帝国襲来編4】 - Show: 歴史を面白く学ぶコテンラジオ （COTEN RADIO） - Published: 2026-09-24 - Canonical: https://podc.club/en/episode/1450522865_fd3673ed6cd0.html - Audio: https://anchor.fm/s/8c2088c/podcast/play/125387142/https%3A%2F%2Fd3ctxlq1ktw2nl.cloudfront.net%2Fstaging%2F2026-8-8%2F85b24570-4ae1-1ddc-5362-17229e0b882b.mp3 - Source: Edited from a machine transcript of the first 30 minutes of the episode. Not an official summary. In 1268, a Mongol imperial letter arrived at Dazaifu via a Goryeo envoy, demanding that Japan submit to Kublai Khan's authority. The Japanese court deliberated and chose not to reply — stalling for time while ordering prayers at twenty-two shrines and temples. This episode traces the diplomatic confrontation on the eve of the Bun'ei invasion, from the geopolitical logic behind Kublai's demand to the blunt military ultimatum delivered in a second letter roughly a year and a half later. ## What this episode answers ### What exactly did the Mongol imperial letter say, and what threat did it contain? The letter opened with a grand address from the Mongol Emperor to the King of Japan, listed nations that had submitted since Chinggis Khan, and demanded Japan send an envoy and establish relations; it closed with the line "who would willingly resort to arms?", an implicit threat of military force if Japan refused. ### Why did Goryeo resist acting as intermediary between the Mongols and Japan, and how did it try to avoid the role? Goryeo had no desire for war with Japan and was exhausted from about thirty years of fighting the Mongols, so it dragged its feet — for example demolishing a Hakata compound used for contact with Japanese residents to hide evidence of ongoing contact — though Kublai saw through this each time and pushed the negotiating role back onto Goryeo. ### What did the imperial court actually do after receiving the Mongol letter? After Dazaifu forwarded the letters to the Kyoto court, the court debated and decided to send no reply at all (a draft response was written but never sealed), while ordering twenty-two shrines and temples to pray for the submission of foreign enemies. ### Why did the Mongols insist on Japan's submission before completing their conquest of the Southern Song? Kublai's paramount goal was conquering the Southern Song, and Japan was supplying sulfur (a key gunpowder ingredient) to the Song through private trade, which alarmed the Mongols; since Japan had no formal ties with the Song but flourishing private commerce, Kublai read this as an alliance and wanted Japan brought under his control before completing the Song's encirclement. ### How did the second Mongol letter differ from the first? The second letter dropped the hedged, courteous tone of the first and became a direct ultimatum: submit and send an envoy by the coming spring for treatment equal to Goryeo, or the khan would mobilize warships and subjugate Japan by force. ## Article ## Goryeo Caught in the Middle: Guide Our Envoy to Japan Kublai Khan ordered Goryeo (고려) to escort a Mongol envoy all the way to Japan — and made clear in advance that "rough seas" would not be accepted as an excuse. Goryeo complied reluctantly. At one point the guides tried to show the envoy how high the waves were off Tsushima, hoping to abort the mission, and were reprimanded for it. Goryeo had no reason to want war with Japan and was exhausted after roughly thirty years of fighting the Mongols. In Hakata, a compound that had served as a meeting place for Japanese residents was quietly demolished so that evidence of ongoing contact with Japan would disappear. Every act of foot-dragging, however, was seen through by Kublai, who responded each time by pushing the responsibility for negotiating with Japan back onto Goryeo. ## The Mongol Letter: Demands Wrapped in Courteous Language In 1268, a Goryeo envoy named Panpu arrived at Dazaifu — at the time Japan's only official gateway to the outside world — carrying two documents: a Mongol imperial letter and a separate letter from Goryeo King Wonjong. The imperial letter opened with "Under the grace of Heaven, the Emperor of Great Mongolia addresses the King of Japan." It enumerated the many nations that had submitted since the time of Chinggis Khan, cited the return of prisoners after Goryeo's conquest as evidence of benevolent rule, and then came to its point: Japan was geographically very close to Goryeo yet had never once sent an envoy; surely this was only because Japan was unaware of the situation; Japan should send an envoy promptly and establish a formal relationship; a sage regards the four seas as his home — who would willingly resort to arms? That final line carried the implicit military threat. Wonjong's letter was somewhat softer in tone, amounting to: "You might consider sending a probing envoy. Though I should warn you, submission is almost certain to follow." The text made plain that Goryeo's own allegiance to the Mongols was far from wholehearted. ## Japan's Response: Silence and Prayers Dazaifu forwarded the letters to the imperial court in Kyoto. After debate, the conclusion was to send no reply. A draft response was actually written, but no seal was affixed. The podcast draws a parallel with the arrival of Commodore Perry's fleet in the nineteenth century, when the shogunate solicited opinions from the domains and then deliberately avoided giving a definitive answer. As long as no reply was sent, negotiations could be stretched out indefinitely — the strategy was to keep stalling until the other side gave up. What the court did in practice was issue orders to twenty-two shrines and temples to pray for the submission of foreign enemies (ikoku kōfuku kitō). For people of the era, the power of the gods and buddhas was a practical force of a kind that has no modern equivalent — this was the era's first resort. Around the same time, at Iwashimizu Hachimangū in Kyoto, a bag holding a sacred sword was found gnawed through by mice, and a divination declared that an event shaking the realm was imminent. The imperial palace burned the following year, and the Mongol forces arrived the year after that; people looked back and shuddered that the omen had proved accurate. The shogunate sent word to military governors across the country that the Mongols were demanding submission and that they should be on alert. Where a modern military alliance would specify exactly what to prepare and by when, the message amounted to a single instruction: be careful. Partly this reflected the feudal structure, in which the shogunate lacked direct authority to order the domains. But it also exposed Japan's weak grasp of foreign affairs — the country had had no formal diplomatic relations with any state for centuries and had never fought a full-scale external war. ## Why the Mongols Wanted Japan's Submission Kublai's paramount objective was the conquest of the Southern Song dynasty in southern China. Japan and the Southern Song maintained active private trade, and one commodity in particular alarmed the Mongols: sulfur. Japan, a volcanic archipelago, exported sulfur that served as a key ingredient in the Southern Song's gunpowder and thus underpinned its military capacity. From Kublai's perspective, Japan was materially supporting an enemy state. Hakata was home to a large community of Song merchants, prominent among them as "Hakata kōshu" — leaders of trade consortia — who patronized shrines such as Hakozaki. One well-known Song merchant, Xie Guoming (謝国明), sponsored the Tang monk Shōichi Kokushi and funded the construction of Shōfukuji temple in Hakata. Shōfukuji is also credited as the birthplace of udon and soba, with a stone monument on the grounds to mark the fact — a reminder that Hakata, despite its reputation for ramen, has deep roots as a noodle city of a different kind. Japan sat outside the Chinese tributary order and had no formal state-to-state relations even with the Southern Song — only flourishing private commerce. Kublai interpreted this relationship as an alliance and wanted Japan brought inside his orbit before he completed the encirclement of the Southern Song. ## The Second Letter: Escalation to an Ultimatum About a year and a half after the first letter was ignored, a second envoy, Kim Yu-seong (金有成), arrived at Tsushima during the rule of regent Hōjō Tokimune. The stated pretext was the return of two Tsushima islanders who had earlier been taken captive; the real purpose was to deliver another letter. The second letter was unrecognizable in tone. It stated plainly: send an envoy and pledge allegiance by the coming spring, and Japan would be guaranteed treatment equal to Goryeo's; fail to do so, and the khan would order his generals to mobilize warships and subjugate Japan by force. The carefully hedged closing line of the first letter — "who would willingly resort to arms?" — had been replaced by a direct military ultimatum. Being ignored once, the podcast suggests, led Kublai to conclude that polite language was not working. ## Takeaways - Goryeo, exhausted by thirty years of Mongol war and lacking any interest in conflict with Japan, repeatedly tried to dodge the intermediary role — even destroying a Japanese community facility in Hakata — but Kublai saw through every maneuver and kept forcing the responsibility back onto Goryeo. - The imperial court responded to the 1268 Mongol letter with a deliberate non-reply, stalling for time while ordering prayers at twenty-two shrines and temples — a pattern the podcast likens to the shogunate's calculated evasiveness when Perry arrived nearly six centuries later. - Kublai demanded Japan's submission because Japanese sulfur exports were fueling the Southern Song's military, and when silence met his first letter, the second — delivered to Tsushima under regent Hōjō Tokimune — dropped all diplomatic softening and issued a deadline: submit by spring or face invasion.