Definition: between 1949 and 1990, this portion of germany's largest city was occupied and run by communist forces.

The correct answer is East Berlin.

After World War II, Berlin was split into East and West Berlin. West Berlin was controlled by the US, Great Britain, and France. East Berlin was controlled by the Soviet Union. During this time, the Soviet Union used a system of communism. Eventually, the split between these two cities would be represented by the Berlin Wall, which lasted over two decades.