Research on historic environments of ancient Japan regarding the negotiation with Bo Hai and the trade route to the Bo Hai imperial castle

对古代日本与渤海之间的谈判情况进行了个别时期的帝王城堡搬迁评估。从历史和考古的角度阐明了以下发现：在渤海早期，日本与翰林堡和御用城堡（中京、东京）所在的延边地区（渤海）的互动，是由图门江、海兰河、布尔哈通河周围的水道和道路所推动的。上京-龙神府中后期通过牡丹江流域的航线与面向“日本海”的日本港（称为“祖”）相连。

The negotiation situations between ancient Japan and Bo Hai were evaluated for individual periods of relocation of imperial castles. The following findings are elucidated in historical and archaeological ways:1. The interactions between Japan and Yanbian area (Bo Hai), where the residence castle and the imperial castles (Zhongjing and Dongjing castles) were located during the early period of the Bo Hai, were promoted by the routes of the channels and roads around Tumenjiang, Hailanhe, and Buerhatonghe.2. Shangjing-Longshenfu during its middle and latter periods was connected to Japanese harbor (called “Tsu”) facing "Japan Sea" via the routes of Mudan Jiang basin.