It is considered to have founded to protect Omi no miya from Togoku (the eastern part of Japan, particularly Kanto region) in the period of Emperor Tenchi, its scale could have been either equaling or surpassing gunga (county government offices) and gundan (military service).
天智天皇の頃に近江宮を東国から防衛するために設けられたとされ、郡衙や軍団(古代日本)と同等以上の規模だったと考えられる。