After the Battle of Sekigahara, tozama daimyos (non-hereditary feudal lords), who were transferred to other domains with substantial additional properties, built one castle after another and also reconstructed many preexisting castles.
関ヶ原の戦い後、各地に移封され、大幅に加封された外様大名達によって次々に城が建設され、既存の城も多くで改築を施された。