Since the „two plus four“ treaty was a multilateral agreement, not all contracting parties received an original, unlike bilateral treaties. In the case of multilateral contracts, one of the parties is generally custodian, so the document kept in the political archives of the Ministry of Foreign Affairs is the only original copy of the treaty. Between May and September 1990, the foreign ministers of the Federal Republic of Germany, the GDR, France, Russia, Great Britain and the United States discussed these points several times – and finally agreed after lengthy negotiations. On 12 September 1990, they signed the „two plus four“ treaty in Moscow, named after the groups of countries concerned. On 1 October 1990, in a joint declaration in New York, the four victorious powers of the Second World War renounced their rights vis-à-vis Germany, thus granting full sovereignty to the Federal Republic. On March 15, 1991, the „two plus four“ treaty came into force. It was the foreign policy complement to the unification treaty between the FRG and the GDR. In the shadow of Helmut Kohl, Hans-Dietrich Genscher silently organized the reunification of Germany. The agreement was a diplomatic masterpiece. Now his party has organized a 25th anniversary celebration in his honour. The fall of the Berlin Wall marked the beginning of a new era, but it was the two plus four treaty that paved the way for German reunification. On 2 August 1945, the Potsdam Agreement, proclaimed at the end of the Potsdam Conference, agreed, among other things, on the initial conditions under which the World War II Allies were to rule Germany.
A temporary German-Polish border, known as the Oder-Neisse line, has in theory attributed most of the German provinces in eastern Germany to Poland and the Soviet Union as part of this „temporary border“. The German population in these areas has been displaced or killed. These agreements were provisional and the agreement provided that the situation would be concluded by „a peace settlement for Germany accepted by the German government if an appropriate government is formed“ (Potsdam Agreement 1.3.1).