 He negotiated the German reunification in 1990 with his counterpart from the GDR, Markus Meckel.On 12 September 1990 he signed the Treaty on the Final Settlement with Respect to Germany on behalf of West Germany.In November 1990, Genscher and his Polish counterpart Krzysztof Skubiszewski signed the German-Polish Border Treaty on the establishment of the Oder–Neisse line as Poland's western border.