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.