Sekiyado is located at the confluence of the Tone River and the Edogawa River, and was thus a strategic location controlling river traffic in the northern Kantō region, as well as the northeastern approaches to Edo. A fortification was built on this location in the early Muromachi period by either Yadoya Mitsusuke (1395-1438) or Yadoya Shigesuke (d. 1512). It was destroyed during a campaign by the Late Hōjō clan of Odawara to conquer the Kantō region from 1565-1574.