Due to their proximity to the Ara-kara River and Tone-gawa River (present-day, Furutone-gawa River and Naka-gawa River) estuaries, the ports of Edo and Shinagawa served as important hubs for riverine transportation from inland areas of the northern Kanto to places such as Kamakura and Odawara Castle, and locations as far as western parts of Japan.
江戸や品川は利根川（現在の古利根川・中川）や荒川(関東)などの河口に近く、北関東の内陸部から水運を用いて鎌倉・小田原城・西国方面に出る際の中継地点となった。