In the time of Dokan, the Hirakawa River (present-day, Kanda-gawa River and Nihonbashi-gara River in Tokyo) poured into Hibiya inlet, and the area around Edo Maejima east of the Hibiya cove and west of the Edo-minato Port served as an influential port of Musashi Province during the medieval period rivalling the ports of Asakusa and Shingawa (however, in the "Tokyoshi Shiko", Hibiya inlet is identified as Edo-minato Port).
道灌の時代、現在の神田川(東京都)並びに日本橋川の前身である平川（平河）は日比谷入江に流れ込んでおり、西に日比谷入江、東に江戸湊（但し『東京市史稿』は日比谷入江を江戸湊としている）がある江戸前島周辺は中世には、浅草や品川湊と並ぶ、武蔵国の代表的な湊であった。