Even from its most ancient times Japan already possessed the system of barrier checkpoints; among the barriers of ancient Japan, three, namely the Suzuka-no-seki barrier along the Tokaido Road, the Fuwa-no-seki barrier on the Tosando Road, and the Arachi-no-seki barrier along the Hokurikudo Road, were considered especially significant given their intended roles of guarding the entrances to the Kinai region (the central region around the capital), and were thus termed the sangen (the three major barrier stations).
日本では古代に既に制度化されており、東海道の鈴鹿関、東山道の不破関、北陸道の愛発関が畿内を防御するために特に重視され、これを三関という。