Republic of Buryatia in the context of "Uda River, Buryatia"

Lake Baikal is a rift lake and the deepest lake in the world. It is situated in southern Siberia, Russia between the federal subjects of Irkutsk Oblast to the northwest and the Republic of Buryatia to the southeast.

At 31,722 km (12,248 sq mi)—slightly larger than Belgium—Lake Baikal is the world's seventh-largest lake by surface area, as well as the second largest lake in Eurasia after the Caspian Sea. However, because it is also the deepest lake, with a maximum depth of 1,642 metres (5,387 feet), Lake Baikal is the world's largest freshwater lake by volume, containing 23,615.39 km (5,670 cu mi) of water or 22–23% of the world's fresh surface water, more than all of the North American Great Lakes combined. It is also the world's oldest lake at 25–30 million years, and among the clearest. It is estimated that the lake contains around 19% of the unfrozen fresh water on the planet.

The Buryats are a Mongolic ethnic group native to southeastern Siberia who speak the Buryat language. They are one of the two largest indigenous groups in Siberia, the other being the Yakuts. The majority of the Buryats today live in their titular homeland, the Republic of Buryatia, a federal subject of Russia which sprawls along the southern border and partially straddles Lake Baikal. Smaller groups of Buryats also inhabit Ust-Orda Buryat Okrug (Irkutsk Oblast) and the Agin-Buryat Okrug (Zabaykalsky Krai) which are to the west and east of Buryatia respectively as well as northeastern Mongolia and Inner Mongolia, China. Traditionally, they formed the major northern subgroup of the Mongols.

Buryats share many customs with other Mongolic peoples, including nomadic herding, and erecting gers for shelter. Today the majority of Buryats live in and around Ulan-Ude, the capital of the Buryat Republic, although many still follow a more traditional lifestyle in the countryside. They speak a central Mongolic language called Buryat. UNESCO's 2010 edition of the Atlas of the World's Languages in Danger classifies the Buryat language as "severely endangered".

Kyakhta (Russian: Кя́хта, [ˈkʲæxtə]; Buryat: Хяагта, romanized: Khiaagta, [ˈçæːχtə]; Mongolian: Хиагт, romanized: Hiagt, [ˈçæχtʰ]) is a town and the administrative center of Kyakhtinsky District in the Republic of Buryatia, Russia, located on the Kyakhta River near the Mongolia–Russia border. The town stands directly opposite the Mongolian border town of Altanbulag. Population: 20,041 (2010 census); 18,391 (2002 census); 18,307 (1989 Soviet census). From 1727 it was the border crossing for the Kyakhta trade between Russia and China.

The Selenga (/ˌsɛlɛŋˈɡɑː/ SEL-eng-GAH) or Selenge is a major river in Mongolia and Buryatia, Russia. Originating from its headwater tributaries, the Ider and the Delger mörön, it flows for 992–1,024 kilometres (616–636 mi) before draining into Lake Baikal. The Selenga therefore makes up the most distant headwaters of the Yenisey-Angara river system.

Carrying 935 cubic metres per second (33,000 cu ft/s) of water into Lake Baikal, it makes up almost half of the riverine inflow into the lake, and forms a wide delta of 680 square kilometres (260 mi) when it reaches the lake.