way traverses the Grassy Zone from Chelyabinsk, the station at the eastern foot of the Ural Mountains where the lines from Petrograd and Moscow unite, to Irkutsk on the Angara River just below its exit from Lake Baikal. Wheat-fields are beginning in large measure to replace the grass along the line of the railway, but the thread of settled population is still a narrow one, and the Tartar and Khirghiz horsemen are still nomad over wide areas.
The edge of the forest bends southward along the boundary between Western and Eastern Siberia, for Eastern Siberia is filled with forested mountains and hills, which fall in elevation gradually from the Transbaikalian Plateau into the north-eastern promontory of Asia towards Behring Strait. The Grassy Zone bends south with the forest and continues eastward over the lower level of the Mongolian uplands. The slope upward from the Great Lowland into Mongolia is through the 'Dry Strait' of Zungaria, between the Tianshan Mountains on the south and Altai Mountains on the north. Beyond Zungaria the steppes, now at upland level, continue round the southern edge of the forested Altai and Transbaikalian Mountains, with the Gobi Desert to the south of them, until they reach the upper tributaries of the Amur
