In 1949, Germany had divided into West German and East Germany. West Germany received Marshall Aid and so living standards and salaries became much higher than in East Germany
The government in East Germany was unpopular and there were riots against it in 1953
EastGermans could easily travel to Berlin, cross from East Berlin to West Berlin, and then travel freely from West Berlin to West Germany
By 1958, three million East Germans had crossed to the West. This was over a sixth of the population
Consequently, lots of problems were caused for EastGermany, as a lot of the people were leaving were engineers,technicians and teachers, who they needed to help rebuild the economy
Consequently, Khrushchev issued the Berlin Ultimatum and eventually built the Berlin Wall