The Mun River sometimes spelled Moon River, is a tributary

Tributary

A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...

 of the Mekong

Mekong

The Mekong is a river that runs through China, Burma, Laos, Thailand, Cambodia and Vietnam. It is the world's 10th-longest river and the 7th-longest in Asia. Its estimated length is , and it drains an area of , discharging of water annually....

 river. It carries approximately 21,000 cubic kilometres of water per year.

Geography

It rises in the Khao Yai

Khao Yai National Park

Khao Yai National Park is a national park in Thailand.-Description:Khao Yai National Park is situated in the Sankamphaeng Mountain Range, the southern prolongation of the Dong Phaya Yen Mountains, at the southwestern boundary of the Khorat Plateau....

 National Park area of the Sankamphaeng Range, near Nakhon Ratchasima

Nakhon Ratchasima

Nakhon Ratchasima or is a city in the north-east of Thailand and gateway to Isan. It is the capital of the Nakhon Ratchasima Province and Nakhon Ratchasima district...

 in the Isan

Isan

Isan is the northeastern region of Thailand. It is located on the Khorat Plateau, bordered by the Mekong River to the north and east, by Cambodia to the southeast and the Prachinburi mountains south of Nakhon Ratchasima...

 area of Thailand

Thailand

Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...

. It then flows east through the Khorat Plateau

Khorat Plateau

The Khorat Plateau also Korat Plateau, is a plateau in the northeastern region of Thailand, named for the short form of Nakhon Ratchasima, an historical stronghold controlling access to and from the plateau.-Geography:...

 in southern Isan (Buriram

Buriram Province

Buri Ram or is one of the north-eastern provinces of Thailand. Neighboring provinces are Sa Kaeo, Nakhon Ratchasima, Khon Kaen, Maha Sarakham and Surin. To the south-east it borders Oddar Meancheay of Cambodia...

, Surin

Surin Province

Surin is one of the north-eastern provinces of Thailand. Neighboring provinces are Buriram, Maha Sarakham, Roi Et and Sisaket...

 and Sisaket

Sisaket Province

Sisaket , is one of the north-eastern provinces of Thailand. Neighboring provinces are Surin, Roi Et, Yasothon and Ubon Ratchathani. To the south it borders Oddar Meancheay and Preah Vihear of Cambodia.-Geography:...

 provinces) for 466 miles (750 km) until it joins the Mekong at Khong Chiam

Amphoe Khong Chiam

Khong Chiam is the easternmost district of Ubon Ratchathani Province of Thailand.-History:The area of the district was the central district Khwaeng of Mueang Khong Chiam, which is now Si Mueang Mai district...

 in Ubon Ratchathani

Ubon Ratchathani Province

-History:The area was part of the Khmer Empire. Before the late eighteenth century, this area evidently was outside Siamese or Thai Ayutthaya Kingdom....

. The Moon River's main tributary is the Chi River

Chi River

The Chi River is the longest river in Thailand; it extends 765 km, but carries less water than the second longest river, the Mun. In the Isan dialect of this region, and also in the adjacent language Lao, the name of the river is actually pronounced "Nam Si" but the transliteration Chi...

, which flows into it in Kanthararom district

Amphoe Kanthararom

Kanthararom is a district in the northeastern part of Sisaket Province, northeastern Thailand.-History:The district was established in 1897, then named Uthai Sisaket . It was renamed to Kanthararom in 1913...

 of Sisaket province

Sisaket Province

Sisaket , is one of the north-eastern provinces of Thailand. Neighboring provinces are Surin, Roi Et, Yasothon and Ubon Ratchathani. To the south it borders Oddar Meancheay and Preah Vihear of Cambodia.-Geography:...

.

History

The Mun River used to be known as 'Moon River' by U.S. Air Force personnel stationed at Ubon Ratchathani

Ubon Ratchathani

Ubon Ratchathani is a city on the Mun River in the south-east of the Isan region of Thailand. It is known as Ubon for short. The name means "Royal Lotus City." The provincial seal features a pond with a lotus flower and leaves in a circular frame. Ubon is the administrative centre of Ubon...

 airbase during the Vietnam War

Vietnam War

The Vietnam War was a Cold War-era military conflict that occurred in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. This war followed the First Indochina War and was fought between North Vietnam, supported by its communist allies, and the government of...

.

The controversial Pak Mun dam

Pak Mun dam

The Pak Mun Dam is a gravity dam located 5.5 km west of the confluence of the Mun and Mekong rivers in Ubon Ratchathani province, Thailand...

is located near the confluence with the Mekong.