The factor that made it easy for communism to spread in Eastern Europe is because "Many people were unhappy with their governments."
This is evident in the fact that after world war 1, Stalin used the power of propaganda through radio to popularize the defects of the governments in eastern Europe.
He also secretly recruit policemen to spread Communism in the region. A good example was how he recruited police forces that were unhappy with the government in Poland in 1939.
