Tōsandō

is a Japanese term for both an ancient division of the country and the main road running through the region. 
History.
"Tōsandō" 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 "Tōsandō", remained cultural markers. 
Geography.
"Tōsandō" is in the central mountains of northern Honshū. It is made of eight ancient provinces, including
After 711, Tōsandō was understood to include Musashi province.
The lands of many prefectures are in the region of "Tōsandō": Akita, Aomori, Fukushima, Fiu, Gunma, Iwate, Miyagi, Nagano, Shiga and Tochigi prefectures.