Answer:
Because of Allied Victory
Explanation:
During WW1, the Victors were the Allies (US, UK, France, among others). The only territorial change was Alsace-Lorraine, which was land taken by France from Germany.
The Russian Empire collapsed in 1917, as the result of the overthrow of the monarch, during the February Revolution. However, not everyone agreed with the provisional government. This led to uprisings and the most popular opponents of this government were the Communist, also known as the Bolsheviks, led by Vladimir Lenin. This caused the October Revolution, which led to the Russian Civil War between the Bolsheviks (Red Army) and the White Army. The war finally came to an end in December 1922. The Union of Soviet Socialist Republics (USSR), also known as the Soviet Union, was created. Vladimir Lenin will go on and lead the new country until his death in 1924, and was succeeded by Joseph Stalin. The main reason of the creation of the Soviet Union was the fact that people did not have any food, were loosing WW1, and their monarch was weak and corrupt. This is where Vladimir Lenin, who believed in the ideas of the Communist Manifesto written by Karl Marx, started to share the ideas with the Russian People. Thus leading to the civil war.
