Suō Province

In terms of the Gokishichidō system, Suō was one of the provinces of the San'yōdō circuit.

Under the Engishiki classification system, Suō was ranked as one of the "superior countries" (上国) in terms of importance, and one of the "far countries" (遠国) in terms of distance from the imperial capital, Kyoto.

These were united to form the Ritsuryo province, which initially consisted of five counties: Oshima, Kumage, Tsuno, Sawa, and Kisiki.

In the Asuka period, the Iwakisan Kōgoishi mountain fortification was constructed against a possible invasion by Tang dynasty China and the Kingdom of Silla in Korean peninsula.

[3] Per the early Meiji period Kyudaka kyuryo Torishirabe-chō (旧高旧領取調帳), an official government assessment of the nation’s resources, the province had 295 villages with a total kokudaka of 548,861 koku.