Bokkaishi (delegate from Bo Hai) (渤海使)
Bokkaishi was the envoy to Japan from Bo Hai, and a record stated there were 34 visits (one visit from the Liao Dynasty) of the envoy during 728 to 922.
Background and Summary
Bo Hai was founded by Jo-yeong DAE in 698, but it became opposed to the Tang Dynasty and Silla in the period of Muye DAE, and it was planned to dispatch an envoy to Japan in order to warn against the power. The envoy had strong suggestion of military alliance at the initial stage, and Japan side treated the envoy from Bo Hai very well as Japan viewed it as he/she visited Japan by the emperor's influence by virtue.
However, when it became the period of Heummu DAE and of reconciliation with Tang, its military implication wore off and changed its characteristics to the envoy for cultural exchange and economic activities. The problem was that it took the style of tribute trade, so Japan was obligated to return severalfold kaishi (return gift) to correspond to a tribute from Bo Hai and produced great profit to Bo Hai. After tax collection capability by the Imperial Court diminished and the expenses for entertaining the envoy and kaishi became burden, Japan side added the limitations to have the envoy's visit once in 12 years, but the exchange had continued until the fall of Bo Hai.
Intermediary role of Tang Dynasty and Japan
With the stabilization of the relationship between Tang and Bo Hai, Bokkaishi functioned as the intermediate for the transportation between Japan and Tang.
After the late eighth century, the main items were fell from the northern islands and textile, gold, and mercury from Japan.
List of Bokkaishi
The 35th envoy was the envoy from Dongdan who called himself Bokkaishi. Tenken was the era of Liao.