In ancient times a border area between Musashi-no-kuni and Shimo-usa-no-kuni, called the Nakagawa Lowlands, had not become solid land and was therefore unsuitable as a travel route, but Musashi-no-kuni belonged to Tozando under the traditional influence of the powerful families of its northern neighbor Ueno-no-kuni, and had a close relationship with them (see the article on Musashi-no-kuni-nomiyatuko-no-ran).
武蔵国と下総国の境の中川低地付近は古代には陸化が進んでおらず低湿地で通行に適さず、元来武蔵国が北隣の上野国の豪族の影響下にありその関係が密接であった（武蔵国造の乱を参照のこと）。