甲州街道
With the establishment of the Tokugawa shogunate, Kai was regarded as strategically important to the defense of Edo due to its position between the Tōkaidō and Nakasendō highways, which were connected through Kai Province by the Kōshū Kaidō. Kai Province was entrusted briefly to Tokugawa clan members or the highly trusted Yanagisawa clan as Kōfu Domain, but for the most part was retained as "tenryō" territory ruled directly by the shogunate through a succession of "hatamoto"-class "daikan."