The San'yō Region (山陽地方 San'yō-chihō) is an area in the south of Honshū, the main island of Japan.[1] It consists of the southern part of the Chūgoku region, facing the Seto Inland Sea. The name San'yō means "southern, sunny (yō) side of the mountains" and contrasts with the San'in or "northern, shady (in) side of the mountains".
The region is generally considered to include the prefectures of Okayama, Hiroshima and Yamaguchi. Sometimes, the section of Hyōgo Prefecture that formerly comprised Harima Province is considered to be within the region as well.
The San'yō encompasses the pre-Meiji provincial areas of Harima, Mimasaka, Bizen, Bitchu, Bingo, Aki, Suō and Nagato.[2]
The region is served by the San'yō Main Line and Sanyō Shinkansen.
The San'in subregion is a subregion of Chūgoku region that composes of the prefectures of Shimane, Tottori, and sometimes the northern portion of Yamaguchi Prefecture. The northern portion of Yamaguchi Prefecture composes of Abu, Hagi, and Nagato. The San'yo subregion is a subregion of Chūgoku region and is composed of the prefectures of Hiroshima, Okayama, and Yamaguchi in its entirety.
Per Japanese census data,[3] and,[4] San'yo subregion has had positive population growth throughout the 20th century and negative population growth since the beginning of 21st century.