Buryatia, officially the Republic of Buryatia, is a republic of Russia located in the Russian Far East. Formerly part of the Siberian Federal District, it has been administered as part of the Far Eastern Federal District since 2018. It borders Irkutsk Oblast and Lake Baikal, the deepest lake in the world to the north, Zabaykalsky Krai to the east, Tuva to the west and Mongolia to the south. Its capital is the city of Ulan-Ude. It has an area of 351,300 square kilometers (135,600 sq mi) with a population of 978,588. It is home to the indigenous Buryats.

Irkutsk Oblast is a federal subject of Russia, located in southeastern Siberia in the basins of the Angara, Lena, and Nizhnyaya Tunguska Rivers. The administrative center is the city of Irkutsk. It borders the Republic of Buryatia and the Tuva Republic in the south and southwest, which separate it from Khövsgöl Province in Mongolia; Krasnoyarsk Krai in the west; the Sakha Republic in the northeast; and Zabaykalsky Krai in the east. It had a population of 2,370,102 at the 2021 Census.