Orkhon River

Orkhon
Native name Орхон (Mongolian)
Location
CountryMongolia
AimagsÖvörkhangai, Arkhangai, Bulgan, Darkhan-Uul, Selenge
Major citiesKharkhorin (Karakorum), Sükhbaatar
Physical characteristics
SourceSuvraga Khairkhan
  locationTsenkher sum, Arkhangai
  coordinates47°2′59″N 101°20′30″E / 47.04972°N 101.34167°E / 47.04972; 101.34167
MouthSelenga
  location
Sükhbaatar city, Selenge aimag
  coordinates
50°15′0″N 106°8′20″E / 50.25000°N 106.13889°E / 50.25000; 106.13889
Length1,124 km (698 mi)
Basin size132,835 km2 (51,288 sq mi)
Discharge 
  locationBulgan
  average66 m3/s (2,300 cu ft/s)
  minimum0.5 m3/s (18 cu ft/s)February
  maximum190.2 m3/s (6,720 cu ft/s)July
Basin features
ProgressionSelengaLake BaikalAngaraYeniseyKara Sea
Tributaries 
  leftTamir River
  rightTuul River, Kharaa River

The Orkhon River (/ˈɔːrkɒn/ OR-kon) is the longest river in Mongolia.

It rises in the Khangai Mountains in the Tsenkher sum of Arkhangai aimag at the foot of the Suvraga Khairkhan mountain. From there, it crosses the border into Övörkhangai aimag and follows the upper Orkhon valley in an eastern direction until it reaches Kharkhorin. On this stretch, very close to the Orkhon, the Ulaan Tsutgalan river features a waterfall, ten metres (33 ft) wide and twenty metres (66 ft) high, which is a popular destination for tourists.

From Kharkhorin it flows northwards until it reaches Bulgan aimag, and then north-east to join the Selenge River next to Sükhbaatar city in Selenge aimag, close to the Russian border. The Selenge then flows further north into Russia and Lake Baikal.

With 1,124 km (698 mi), the Orkhon is longer than the Selenge, making it the longest river in Mongolia. Major tributaries of the Orkhon river are the Tuul River and Tamir River.

There are two sets of ancient ruins along the river valley: Khar Balgas, the ancient capital of the Uyghur Kingdom and Karakorum, the ancient capital of the Mongol Empire. Pyotr Kuzmich Kozlov excavated several Xiongnu Imperial tombs in the area of the river valley.

Fish in the Orkhon River include pike, carp, perch, taimen and catfish.

UNESCO lists the Orkhon Valley as a World Heritage Site.