Gan River is a tributary of the Nen River

Nen River

Nen River or Nenjiang , or Nonni is a river in Northeast China. The Nen River flows through the northern part of Heilongjiang Province and the northeastern section of Inner Mongolia, some parts of the river forming the border between the two regions...

 in Inner Mongolia

Inner Mongolia

Inner Mongolia is an autonomous region of the People's Republic of China, located in the northern region of the country. Inner Mongolia shares an international border with the countries of Mongolia and the Russian Federation...

, China

China

Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

. It flows 446 km from the east flank of the Greater Khingan

Greater Khingan

The Greater Khingan Range , also called the Greater Hing'an Range or Greater Hinggan Range, is a volcanic mountain range in the northeastern part of the People's Republic of China. The range extends roughly 1,200 km from north to south, narrowing towards the south...

 Range into the Nen River at Nenjiang

Nenjiang

Nenjiang may refer to:* Nen River , one of the major tributaries to the Songhua River in Heilongjiang province, China* Nenjiang County, a county under Heihe city, Heilongjiang, China...

, through the Morin Dawa Daur

Morin Dawa Daur Autonomous Banner

Morin Dawa Daur Autonomous Banner is one of three autonomous banners in Inner Mongolia, People's Republic of China, created for the Daur people. It lies on the Nen River, borders Heilongjiang province to the east, south, and southwest, and is under the administration of Hulunbuir City.-References:*...

 and the Oroqin Autonomous Banner

Oroqin Autonomous Banner

Oroqin Autonomous Banner is an autonomous banner that lies directly south of the urban district of Hailar in the prefecture-level city of Hulunbuir. It has an area of 60,378 km ². According to the 2000 census, there are 292,097 inhabitants with a population density of 4.84 inhabitants per km²...

 of the vast Hulunbuir

Hulunbuir

Hulunbuir is a region that is governed as a prefecture-level city in northeastern Inner Mongolia, in the People's Republic of China. Its administrative center is located at Hailar District, its largest urban area. Major scenic features are the high steppes of the Hulun Buir grasslands, the Hulun...

 Municipality. It drains an area of over 20,000 sq. km. of mostly hills and plains. The Gan River basin is traditionally home to semi-nomadic Daur and Oroqen people.