Answer:
The shifting borders created new political and cultural boundaries
Step-by-step explanation:
Eastern Europe became a buffer zone for the USSR. During the WW2 communism began to spread and take over the countries that became loyal to Moscow. The newly appointed governments depended directly from the Soviet leader Stalin. A so called Iron curtain emerged as a political and cultural boundary that separated capitalist and free market economes from state planned ones.
By 1949, East Europe was communist, except Yugoslavia.
The East became alligned with the Soviet Union in a pursuit for creating a new world based on the premise that socialism and communist rule will enhace the conditions and recover them from the horrors of war.
The clash between West and East often ocurred along the borderlines , migration was restricted in the countries saw in red: