San'yōdō

San'yōdō (山陽道^?, literally, "southern mountain circuit" or "southern mountain region") is a Japanese geographical term. It means both an ancient division of the country and the main road running through it. The San'yōdō corresponds for the most part with the modern conception of the San'yō region. This name derives from the idea that the southern side of the central mountain chain running through Honshū was the "sunny" side, while the northern side was the "shady" (山陰 San'in) side.

The region was established as one of the Gokishichidō (Five provinces and seven roads) during the Asuka period (538-710), and consisted of the following eight ancient provinces: Harima, Mimasaka, Bizen, Bitchū, Bingo, Aki, Suō and Nagato. However, this system gradually disappeared by the Muromachi period (1333-1467).

The San'yōdō, however, continued to be important, and highly trafficked through the Edo period (1603-1867). Running mostly east-west, its eastern terminus, along with those of most of the medieval highways (街道, kaidō), was at Kyoto. From there it ran west through Fushimi, Yodo, Yamazaki, and Hyōgo; from there it followed the coast of the Seto Inland Sea to Hagi, near Shimonoseki, the western terminus of both the San'yōdō and the San'indō, and very near the westernmost end of the island of Honshū. It ran a total of roughly 145 ri (approx. 350 miles).

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