Trans-Siberian Railway men and ammunition coming from west to east would have to wait in the sidings, whilst troops and injured personnel in a troop train travelling from east to west went along the line. Thus the Japanese were quickly able to advance whilst the Russians were awaiting necessary troops and supplies. After the Russian Revolution of 1917, the railway served as the vital line of communication for the Czechoslovak Legion and the allied armies that landed troops at Vladivostok during the Siberian Intervention of the Russian Civil War. These forces supported the White Russian government of Admiral Alexander Kolchak, based in
Ulan-Ude Okrug. According to the 2010 Census, 404,426 people lived in Ulan-Ude; up from 359,391 recorded in the 2002 Census. In terms of population, it is the third largest city in eastern Siberia. The ethnic makeup of the city's population in 2010: The city is the center of Tibetan Buddhism in Russia and the important Ivolginsky datsan is located from the city. Ulan-Ude is located on the main line (Trans-Siberian line) of the Trans-Siberian Railway between Irkutsk and Chita at the junction of the Trans-Mongolian line (the Trans-Mongolian Railway) which begins at Ulan Ude and continues south through Mongolia to Beijing