Ruins of the ancient Shirakawa Barrier on the Tosan-do highway, one of the three great barriers of Oshu. Established by the ancient court to defend against the northern Emishi, it became celebrated in poetry — by Saigyo, Noin Hoshi, and Minamoto no Yoshiie. Matsuo Basho opens the main journey of "The Narrow Road to the Deep North" by crossing this very barrier. Archaeological surveys confirmed its…

The Shirakawa Barrier is believed to have been established in the late 7th to early 8th century by the ancient Japanese court as a checkpoint at the gateway to Mutsu Province (the Tohoku region). It served as the most important military and administrative barrier on the Tosando highway and is counte…