The Transbaikal oblast was located in Eastern Siberia, to the south and east of Lake Baikal.

The Russians first explored Transbaikalia in 1639, when Maksim Perfilyev sailed up the Vitim River up to the mouth of the Tsipa.

In 1647, Ivan Pokhabov crossed Lake Baikal and, being friends with the Mongols, explored to Urga.

According to the Supreme Decree presented to the Governing Senate on 11 July 1851, the Transbaikal Oblast, consisting of two districts — Verkhneudinsk and Nerchinsky was separated from the Irkutsk Governorate and became its own region (oblast), while Chita was elevated to a city of regional significance.

The Chita district was the most complex, consisting of Cossack villages (stanitsas), peasant volosts, and nomad steppe dumas.

The population was mostly located in 7 cities: Barguzin, Selenginsk, Troitskosavsk, Verkhneudinsk, Chita, Nerchinsk and Aksha, with another 750 settlements as well.