After German reunification, the Federal Republic of Germany and Poland sign a treaty confirming the Oder–Neisse line as the border between Germany and Poland.

German reunification, also known as the expansion of the Federal Republic of Germany (BRD), was the process of re-establishing Germany as a single sovereign state, which began on 9 November 1989 and culminated on 3 October 1990 with the dissolution of the German Democratic Republic and the…