Trans-Siberian Railway imperial collapse, and before the Red Army took control, the Czechs and Slovaks were able to use their organisation and the resources of the railway to establish a temporary zone of control before eventually continuing onwards towards Vladivostok, from where they emigrated back to Czechoslovakia. During World War II, the Trans-Siberian Railway played an important role in the supply of the powers fighting in Europe. During the first two years of the war the USSR had secretly agreed to a neutrality and non-aggression pact with Germany. While Germany's merchant shipping was interdicted by the Western allies, the Trans-Siberian Railway (along
West Siberian taiga Siberian taiga ecoregion, which is colder and more rugged in terrain. The southern edge of the region lies north of the belt of temperate forests and forest-steppe that runs along the Trans-Siberian railway. Because the West Siberian ecoregion is thus outside of the normal agricultural and developed strip of southern Russia, it is sparsely populated, although the city of Yekaterinburg is at the extreme southwest corner of the region. The city of Surgut is the largest city in the interior (with just over 300,000 inhabitants). To the north is the tundra of the Yamal-Gydan tundra ecoregion (covering the Ob River