Open your world atlas to the table of contents and locate a full topographical map of Asia. Political maps may not show rivers, so a geographic map of mountains, lakes, and other natural features is best, especially if it also shows national boundaries.
Locate Mongolia on the map of Asia. It is entirely landlocked, in between northwestern China and southern Russia. It shares no other borders.
Look at Ulaanbaatar, the capital of Mongolia. Notice the Selenga River, which runs directly south of the city. The Selenga, which according to the Concise Dictionary of World Place Names gives its name to a Mongolian province and city, has a more notable distinction: it is the southernmost tributary of the Yenisey system. (See References 2)
Follow the course of the Selenga as it passes through Ulaanbaatar and north into Russia until it flows into Lake Baikal, the largest and deepest lake in the Old World.
Find the western shore of Lake Baikal, out of which the Angara River flows. Trace the Angara northwest as it passes through Irkutsk, the largest city of central Siberia, and north past Bratsk, a region which the Columbia Encyclopedia notes is one of the world's largest sources of hydroelectric power.
Trace the Angara River as it turns west, after which it joins the Yenisey itself. The two rivers form a massive rapids, which is rarely navigable north of their junction.
Notice that the main stream of the Yenisey starts several hundred miles south of the junction with the Angara and flows northward through Krasnoyarsk, another large industrial city of Siberia.
Follow the Yenisey north of the junction with the Angara, as the river heads into the most remote and unpopulated parts of Siberia. Notice the junctions with the Upper and Lower Tunguska rivers, which create an even larger channel for the river's final few hundred miles.
Trace the Yenisey's final reaches as it flows north through the Siberian tundra and the closed Russian city of Dudinka, until it finally drains into the Yenisey Gulf and into the Arctic Ocean.
