In Japanese history, the Yamauchi or Yamanouchi family were a family of rulers over what was then the Tosa Province

Tosa Province

is the name of a former province of Japan in the area that is today Kōchi Prefecture on Shikoku. Tosa was bordered by Iyo and Awa Provinces. It was sometimes called .-History:The ancient capital was near modern Nankoku...

 which spanned the southern half of Shikoku

Shikoku

is the smallest and least populous of the four main islands of Japan, located south of Honshū and east of the island of Kyūshū. Its ancient names include Iyo-no-futana-shima , Iyo-shima , and Futana-shima...

 island.

The province was gifted to the family in 1600 after Yamauchi Kazutoyo

Yamauchi Kazutoyo

' also spelled Yamanouchi , was born the son of Yamanouchi Moritoyo in Owari Province at the end of the Sengoku period of Japan. Kazutoyo held the title of Tosa no kami....

 led troops under Tokugawa Ieyasu

Tokugawa Ieyasu

 was the founder and first shogun of the Tokugawa shogunate of Japan , which ruled from the Battle of Sekigahara  in 1600 until the Meiji Restoration in 1868. Ieyasu seized power in 1600, received appointment as shogun in 1603, abdicated from office in 1605, but...

 at the Battle of Sekigahara

Battle of Sekigahara

The , popularly known as the , was a decisive battle on October 21, 1600 which cleared the path to the Shogunate for Tokugawa Ieyasu...

. The family stayed loyal to the Tokugawa dynasty until shortly before its overthrow in 1868. The head of the family at that time Yamauchi Toyoshige became prince of the newly formed Kochi Prefecture

Kochi Prefecture

is a prefecture of Japan located on the south coast of Shikoku. The capital is the city of Kōchi.- History :Prior to the Meiji Restoration, Kōchi was known as Tosa Province and was controlled by the Chosokabe clan in the Sengoku period and the Yamauchi family during the Edo period.- Geography...

under Imperial rule.