As Wakoku was strengthening its position as a kingdom during the mid-Yayoi period, the defensive aspect of moat settlements as well as upland settlements became more evident to reflect the kingdom's military trend.
倭国における王権形成期とされる弥生時代中期には防御的性格を強め、高地性集落とともに、王権形成過程の軍事的動向を反映していると考えられている。