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Siberian river routes

In the early 17th century, the eastward movement of Russians was slowed by the internal problems in the country during the Time of Troubles. Very soon, exploration and colonization of the huge territories of Siberia resumed, led mostly by Cossacks hunting for valuable furs and ivory. While Cossacks came from the Southern Urals, another wave of Russians came by the Arctic Ocean. These were Pomors from the Russian North, who already had been making fur trade with Mangazeya in the north of the Western Siberia for quite a long time. In 1607, the settlement of Turukhansk was founded on the northern Yenisey River, near the mouth of Lower Tunguska. In 1619, Yeniseysk ostrog was founded on the mid-Yenisey at the mouth of the Upper Tunguska.

Between 1620 and 1624, a group of fur hunters led by Demid Pyanda left Turukhansk and explored some 1,430 miles (2,300 kilometres) of the Lower Tunguska, wintering in the proximity of the Vilyuy and Lena Rivers. According to later legendary accounts (folktales collected a century after the fact), Pyanda discovered the Lena. He allegedly explored some 1,500 miles (2,400 kilometres) of its length, reaching as far as central Yakutia. He returned up the Lena until it became too rocky and shallow, and portaged to the Angara River. In this way, Pyanda may have become the first Russian to meet Yakuts and Buryats. He built new boats and explored some 870 miles (1,400 kilometres) of the Angara, finally reaching Yeniseysk and discovering that the Angara (a Buryat name) and Upper Tunguska (Verkhnyaya Tunguska, as initially known by Russians) are one and the same river.

In 1627, Pyotr Beketov was appointed Yenisei voevoda in Siberia. He successfully carried out the voyage to collect taxes from the Zabaykalye Buryats, becoming the first Russian to step in Buryatia. He founded the first Russian settlement there, Rybinsky ostrog. Beketov was sent to the Lena River in 1631, where in 1632 he founded Yakutsk and sent his Cossacks to explore the Aldan River and farther down the Lena, to found new fortresses, and to collect taxes.

Yakutsk soon turned into a major starting point for further Russian expeditions eastward, southward and northward. Maksim Perfilyev, who earlier had been one of the founders of Yeniseysk, founded Bratsk ostrog on the Angara in 1631. In 1638, Perfilyev became the first Russian to step into Transbaikalia, travelling there from Yakutsk.

In 1643, Kurbat Ivanov led a group of Cossacks from Yakutsk to the south of the Baikal Mountains and discovered Lake Baikal, visiting its Olkhon Island. Ivanov later made the first chart and description of Baikal.