Orkhon

The Orkhon River is the Longest River in Mongolia that travels 698 miles from its headwaters in the Khangai Mountains to its mouth at the Selenga River, which flows north to Russia's Lake Baikal. It rises in the Khangai Mountains in Arkhangai aimag's Tsenkher sum, at the foot of the Suvraga Khairkhan peak. It then crosses the border into vörkhangai aimag and travels east through the upper Orkhon valley until it reaches Kharkhorin. The Ulaan Tsutgalan river contains a waterfall ten meters (33 feet) wide and twenty meters (66 feet) high on this length, quite near the Orkhon, which is a major tourist attraction.

It runs north from Kharkhorin till it reaches Bulgan aimag, then east to join the Selenge River in Sükhbaatar city in Selenge aimag, close to the Russian border. The Selenge then flows farther north into Russia, eventually reaching Lake Baikal. The Orkhon is the longest river in Mongolia, stretching 1,124 kilometers (698 miles) and surpassing the Selenge. The Tuul River and Tamir River are major tributaries of the Orkhon River. Along the river valley, there are two sets of old ruins: Khar Balgas, the ancient capital of the Uyghur Kingdom, and the Karakorum, the ancient capital of the Mongol Empire. Pyotr Kuzmich Kozlov unearthed a number of Xiongnu Imperial tombs in the river valley.

Length: 1,124 km