Berlin was divided into four occupation sectors after World War II.
The Soviet Union controlled the eastern sector, while the United States, the United Kingdom, and France each administered a sector in the west. This arrangement applied even though Berlin was located deep inside the Soviet occupation zone of Germany.
The four sectors created the political geography that later produced divided Berlin. In 1949, the three western sectors developed into West Berlin, while the Soviet sector became East Berlin, the capital of the newly established German Democratic Republic. West Berlin remained politically aligned with West Germany but had a special legal status.
The four-sector arrangement is sometimes confused with the two German states that emerged in 1949. Germany was divided between East and West, but Berlin itself had originally been divided among four victorious Allied powers. The Berlin Wall later separated the western sectors from East Berlin and the surrounding East German territory.