<P> In the early stages of World War II, both Nazi Germany and the USSR invaded and occupied the countries of Eastern Europe after the Molotov--Ribbentrop Pact . Germany then turned against and invaded the USSR: the battles of this Eastern Front were the largest in history . The USSR joined with the Allies and in conferences at Tehran and Yalta, the Allies agreed that Central and Eastern Europe would be in the "Soviet sphere of political influence .". The USSR fought the Germans to a standstill and finally began driving them back, reaching Berlin before the end of the war . Nazi ideology was violently anti-communist, and the Nazis brutally suppressed communist movements in the countries it occupied . Communists played a large part in the resistance to the Nazis in these countries . As the Soviets forced the Germans back, they assumed temporary control of these devastated areas . </P> <P> After World War II, the Soviets ensured that communists loyal to Moscow took power in the countries it occupied . The Soviets retained troops throughout these territories . The Cold War saw these states, bound together by the Warsaw Pact, have continuing tensions with the capitalist west, bound together by NATO . The Chinese Revolution established communism in China in 1949 . </P> <P> During the Hungarian Revolution of 1956, a spontaneous nationwide anti-authoritarian revolt, the Soviet Union invaded Hungary to assert control . Similarly, in 1968, the USSR repressed the Prague Spring by organizing the Warsaw Pact invasion of Czechoslovakia . </P> <P> Labour turmoil in Poland during 1980 had led to the formation of the independent trade union, Solidarity, led by Lech Wałęsa, which over time became a political force . On 13 December 1981, Polish Prime Minister Wojciech Jaruzelski started a crackdown on Solidarity by declaring martial law in Poland, suspending the union, and temporarily imprisoning all of its leaders . </P>

Which region on the map below experienced a post world war ii communist revolution