Kenbokkaishi refers to an envoy sent to Bokkai (Balhae, a kingdom in Manchuria and North Korea, established after the fall of Goguryeo). It is recorded that between 728 and 811 the Kenbokkaishi was dispatched 14 times (one time dispatched as a Japanese envoy to Tang Dynasty China via Bokkai, and one that was a dispatch of navigators).
According to "Shoku Nihongi" (an imperially commissioned Japanese history text), MORO no Kurao, a Watarishima Tsugaru no tsu no tsukasa (official), was dispatched in 720 to take surveys on the local customs in Makkatsu (Mohe (or Malgal, Mogher), a Tungusic people in ancient Manchuria) Province. There is some deliberation in Japan about Makkatasu Province. While Sokichi TSUDA, Hironori MIZUMOTO, Ryosuke KUMATA and Masatoshi ISHII argue that it is a province in Northern Hokkaido, Japan called Ashihase, Kiichi TORIYAMA, Masashi SAKAYORI, Tei MORITA and Akira SEKIGUCHI argue that it is Bokkai, but there is no established theory. According to the latter theory, Bokkaishi (an envoy from Bokkai to Japan) was triggered by the Japanese envoy to Tang Dynasty China in 720, but this has been refuted as well.
Bokkai was founded as a nation by Dae Joyeong in 698, as it became the Dai Bugei (King Mu) period, the kingdom began having conflicts with the Tang Dynasty and Shiragi (Silla, an ancient Korean kingdom). The kingdom made a plan to dispatch an envoy to Japan with the purpose of restraining these powers. The dispatch of the envoy was essentially to establish a military alliance. Japan's perception on the envoy dispatched from Bokkai was that they visited Japan because they were impressed by the virtue of the Japanese Emperor. Japan understood that the envoy was dispatched in order to revitalize Goguryeo, the predecessor of Bokkai, treating the envoy extremely well and dispatching Kenbokkaishi early the following year. In principle, this was the very first Kenbokkaishi.
When there were strong tensions between Shiragi and Bokkai (from 758 to 763), envoys came and went almost every year. In 759, supposedly due to the request of Bokkai, FUJIWARA no Nakamaro planned a full-scale expedition to Shiragi, involving 394 military vessels and 40,700 soldiers. This expedition was cancelled, however, due to discord between Emperor Koken and Oshikatsu as well as changes in the status of Bokkai. When Kinmo DAI reconciled with the Tang Dynasty, envoys no longer implied military activities and were carried out for the sole purpose of cultural exchange and economic activities.
Due to the exchanges being in the form of a tribute trade, Japan was obligated to send return gifts of several times more value after receiving tributes from Bokkai. While this was tremendously beneficial to Bokkai, it pressured Japanese finances. This led to the Japanese government adding a limit to envoy visits to Japan and discontinuing the dispatch of envoys when the expenses for treating them and preparing return gifts could no longer be ignored. Envoys from Bokkai, however, continued to be sent until the downfall of the empire.
Members of the Kenbokkai (according to the "Engishiki" (an ancient book for codes and procedures on national rites and prayers) by Okura-sho shiki); ambassador, hangan (inspector (third highest of the four administrative ranks of the ritsuryo period), rokuji (clerk), osa (translator), shushin (ritual official of dazaifu under the ritsuryo system, governmental office with jurisdiction over Kyushu, Iki and Tsushima), doctor, ommyoji (master of yin yang), shisho (a person handling miscellaneous duties regarding documents), funashi, ite (archer), urabe (fortune teller serving Jingikan, the Department of Worship under the ritsuryo system), tsukahibito, boat-builder, navigator, kenjin (follower), kajitori, and kako (sailor).
List of Bokkaishi Members
The theory that there were 13 dispatches excludes the 4th envoy, and the theory that there were 15 dispatches includes the envoy carried out in 786 (or 720).