In the Tohoku region, where the war against Emishi (natives in Ezo) continued, castles that doubled as a military base and an administrative office, such as Taga-jo Castle, Dewanoki (Dewa Castle), and Akita-jo Castle, were built in the seventh to ninth centuries.
また、蝦夷（えみし）との戦争が続いた東北地方では、7世紀から9世紀にかけて多賀城や出羽柵・秋田城などの軍事拠点と行政拠点を兼ねた城柵が築かれた。