The is a river in Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

 which flows through Gifu Prefecture

Gifu Prefecture

is a prefecture located in the Chūbu region of central Japan. Its capital is the city of Gifu.Located in the center of Japan, it has long played an important part as the crossroads of Japan, connecting the east to the west through such routes as the Nakasendō...

. It is part of the Kiso River

Kiso River

The is a river in Japan roughly 193 km long, flowing through the prefectures of Nagano, Gifu, Aichi, and Mie before emptying into Ise Bay a short distance away from the city of Nagoya. It is the main river of the Kiso Three Rivers and forms a major part of the Nōbi Plain...

 system.

Geography

The river originates in Kakamigahara

Kakamigahara, Gifu

is a city located in the Gifu Prefecture of central Japan. It was founded on 1 April 1963 by the merger of Naka, Sohara, Unuma, and Inaba. Kakamigahara covers a total area of...

, then flows through Gifu

Gifu, Gifu

is a city located in the south-central portion of Gifu Prefecture, Japan, and serves as the prefectural capital. The city has played an important role in Japan's history because of its location in the middle of the country. During the Sengoku period, various warlords, including Oda Nobunaga, used...

, Ginan

Ginan, Gifu

is a town located in Hashima District, Gifu, Japan., the town has an estimated population of 23,856. The total area is 7.90 km².-External links:*...

, Kasamatsu

Kasamatsu, Gifu

is a town located in Hashima District, Gifu, Japan., the town has an estimated population of 22,829. The total area is 10.36 km². The town of Kasamatsu was created in July 1889 when the village of Kasamatsu gained town status.-External links:*...

 and Hashima

Hashima, Gifu

is a city located in the Gifu Prefecture of central Japan.Hashima covers a total area of 87.77 km². As of July 2011 the city has an estimated population of 67,041 inhabitants.The city was founded on 1 April 1954.-External links:*...

, where it flows into the Nagara River

Nagara River

The has its source in the city of Gujō, Gifu Prefecture, and its mouth in the city of Kuwana, Mie Prefecture, Japan. Along with the Kiso River and Ibi River, the Nagara River is one of the Kiso Three Rivers of the Nōbi Plain. Previously, the river was named Sunomata River . With a length of , it...

.

History

Up until the Sengoku Period

Sengoku period

The or Warring States period in Japanese history was a time of social upheaval, political intrigue, and nearly constant military conflict that lasted roughly from the middle of the 15th century to the beginning of the 17th century. The name "Sengoku" was adopted by Japanese historians in reference...

, the lower portion of the Sakai River was the main part of the Kiso River. The river received its name, which means "border river," because it formed the border between Mino

Mino Province

, one of the old provinces of Japan, encompassed part of modern-day Gifu Prefecture. It was sometimes called . Mino Province bordered Echizen, Hida, Ise, Mikawa, Ōmi, Owari, and Shinano Provinces....

 and Owari

Owari Province

was an old province of Japan that is now the western half of present day Aichi Prefecture, including much of modern Nagoya. Its abbreviation is Bishū .-History:The province was created in 646....

provinces.