The German Federal Republic and the German Democratic Republic achieved full political unification in October 1990, thus ending a division between the two separate German states which had been a central problem of the Cold War. Constitutionally unification was achieved by the territories of the former communist GDR becoming part of the Federal Republic, whose legal jurisdiction was now extended to encompass the six new eastern Länder, including Berlin.
The process of unification was precipitated by the collapse of the GDR's communist regime in 1989, which occurred against a background of intense struggle for social and political change throughout Eastern Europe. Widespread popular protest in the GDR, as well as a massive exodus of citizens to the West, made it clear that there was an irreversible demand for democratization and liberalization.
— Keith Taylor
