In September the year before, the envoys from Bokkai washed ashore in Ezochi (inhabited area of Ainu); 16 people including the ambassador Ko Jingi were attacked and killed by the Ezo (the Ainu people), and 8 others including the chieftain Ko Seitoku survived and reached Dewa Province, asking for help.
渤海の使節は前年9月に蝦夷地に漂着し、大使・高仁義ら16名は蝦夷に襲われて死亡、首領・高斉徳ら8名が生き残って出羽国に助けを求めたものであった。