Many of the diplomatic documents from the Joseon Dynasty were often fabricated by the governors of Tsushima Island, who acted as intermediaries between the two countries. This is the first time that the original copy of a diplomatic document between the two has ever been found.

At that time, the governors of Tsushima Island sent their own delegation to Joseon under the feigned name of the shogunate, or manipulated diplomatic documents from Joseon to Japan, as they needed good diplomatic relations between the two countries for the island to ensure stable trade relations with Joseon.

According to the Asahi Shimbun, the diplomatic document was sent from the Joseon Dynasty in 1624 to celebrate the inauguration of Tokugawa Iemitsu as shogun.

The document was discovered in the archives of the Tokyo National Museum by researchers from the Kyushu National Museum and Keio University.

Comparing the document with the Foreign Country Journal, the Passage Prospectus and other documents written by the shogunate, researchers found five discrepancies throughout the document.

For example, the original copy had the phrase, “Also in acknowledgement of your country’s sending a delegation last year.” One part of the phrase, “your country’s sending a delegation last year,” however, was put in a different way in the shogunate’s document. “Tsushima’s sending a delegation,” the phrase in question, means a delegation from the island of Tsushima.

“Your country’s sending a delegation” in the original copy means a congratulatory delegation from the shogunate, but it turned out that the shogunate had never sent a delegation.

The truth is presumed to be as follows: The governor of the Tsushima Island sent a delegation to Joseon under the assumed name of the shogun. When the Joseon Dynasty, believing that it was the official delegation, sent a return courtesy, the governor of the Tsushima Island made up and sent a false document to the shogunate.

Researchers believe that because the official seal of the Joseon Dynasty on the newly discovered copy is different from the existing documents kept by the shogunate, it is highly likely that governors of the Tsushima Island also counterfeited the seal.