In East Siberia the Buriats occupy the Selenga and the Uda, parts of Nerchinsk, and the steppes between Irkutsk and the upper Lena, as also the Baikal Mountains and the island of Orkhon; they support themselves chiefly by live-stock breeding, but some, especially in Irkutsk, are agriculturists.
On the high plateau all attempts to grow cereals have failed, the wide trenches alone (Uda, Selenga, Jida) offering encouragement to the agriculturist.
The Buriats offered some opposition, but between 1631 and 1641 the Cossacks erected several palisaded forts in their territory, and in 1648 the fort on the upper Uda beyond Lake Baikal.
But the trench of the Uda, to the east of Lake Baikal, offers easy access for the Great Siberian railway up to and across the high plateau.
The Shantar Islands in the bay of the Uda possess geological interest.