Tōtōmi province

Tōtōmi Province (遠江国, Tōtōmi-no kuni^?) was a province of Japan in the area of Japan that is today western Shizuoka Prefecture. Tōtōmi bordered on Mikawa, Suruga and Shinano Provinces. Its abbreviated form name was Enshū (遠州^?). The origin of its name is the old name of Lake Hamana.

Tōtōmi was one of the original provinces of Japan established in the Nara period under the Taihō Code. The original capital of the province was located in what is now Iwata, and was named Mitsuke – a name which survived into modern times as Mitsuke-juku, a post station on the Tōkaidō. Under the Engishiki classification system, Tōtōmi was ranked as a "superior country" (上国) in terms of importance, and one of the 16 "middle countries" (中国) in terms of distance from the capital.

During the early Muromachi period, Tōtōmi was ruled nominally by the Imagawa clan before coming under control of the Shiba clan. However, by the Sengoku period, the Imagawa recovered Tōtōmi and effectively annexed it to Suruga Province. After the defeat of the Imagawa at the Battle of Okehazama, Tōtōmi was divided between the powerful warlords Takeda Shingen of Kai and Tokugawa Ieyasu of Mikawa. To consolidate his new holdings, Tokugawa Ieyasu constructed Hamamatsu Castle, which effectively became the capital of the province, although parts of Tōtōmi continued to be contested between the Tokugawa and Takeda until Shingen's death.

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