San'yōdō

is a Japanese term denoting both an ancient division of the country, corresponding for the most part with the modern conception of the San'yō region, and the main road running through it. San'yō translates to "the sunlight-side of a mountain", while dō, depending on the context, can mean either a road, or a circuit in the sense of delineating a 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.
See more at Wikipedia.org...