Originally it referred to the three checkpoints of Fuwanoseki (Mino Province), Suzukanoseki (Ise Province) and Arachinoseki (Echizen Province), but in the early ninth century Arachinoseki was replaced by Osakanoseki (Omi Province).
当初は不破関（美濃国）、鈴鹿関（伊勢国）、愛発関（越前国）の三つを指したが、9世紀初頭に相坂関（近江国）が愛発関に代わった。