San'indō

is a Japanese term for both an ancient division of the country and the main road running through the region. 
History.
"San'indō" was one of the main circuits of the "Gokishichidō" system. It was first established during the Asuka period. Over centuries, the government functions of the "Gokishichido" became less important. However, the traditional eight regions, including "San'indō", remained cultural markers.
Geography.
"San'indō" is the northern part of southern Honshū. The region is on the Sea of Japan. It is a geographic region which has eight ancient provinces, including
The lands of three prefectures is in the region of "San'indō": Kyoto, Hyōgo and Tottori.
Today, Route 9, the San'in Expressway, and the San'in Main Line of the West Japan Railway Company follow the approximate route of the San'indō.