In 1371, in an attempt to prevent opponents joining forces with the wakō, the Hongwu Emperor, founder of the Ming, issued a maritime prohibition on private overseas voyages and commerce.
[3][6] For nearly one hundred and fifty years, until the last such mission in 1547, Chinese "gifts", such as silk thread, brocades, medicines, books, and ceramics, were provided in return for Japanese "tribute", such as lacquerware, bronze vessels, swords, armour, fans, screens, and sulphur (used in papermaking).
[6] Two further dates help frame that of the Japan-Ming trade ship flag: 1567, when the Ming rescinded their maritime prohibitions, and 1592, when Toyotomi Hideyoshi launched his initial invasion of Korea.
[12][16] At this point in Sengoku Japan, after the collapse of the Ashikaga shogunate and the death of unifying warlord Oda Nobunaga in 1582, no central authority was in a position to manage foreign trade and relations, leaving local daimyō free to adopt their own measures.
Contemporary Chinese sources also suggest the central Ming government in Beijing, the "northern capital", was unable fully to control the vessels coming and going from its southern coasts.
[13][6] Dated by its inscription to 1584, the flag was to be raised the following year by a trading ship from Quanzhou in China as a "port entry certificate" in Akamagaseki, now Shimonoseki, in Nagato Province, then in the hands of the Mōri clan, and governed through their daikan (代官), from the Takasu Family.
[12][16][17] From around 1578, family head Takasu Motokane served in the capacity of daikan of Akamagaseki (赤間関代官), his responsibilities ranging from governing this and the neighboring towns to collecting tariffs, managing trade vessels, and mediating disputes, as well as procuring foreign goods for public and private purposes.
[15][16] In 2015, the trade ship flag formed part of the Kyūshū National Museum special exhibition, Sengoku Daimyo: 16th century Warlords' Rivalry in Kyushu over billowing Asian seas.
[19] The Takasu originally from Bingo Province and officiating at Akamegaseki in the Kanmon Straits, gateway to the Inland Sea, there is also a replica of the flag at the Hiroshima Prefectural Museum of History in Fukuyama.