This article relies largely or entirely on a single source. (October 2016)
Bündnis 90 was formed in February 1990 by Neues Forum, Demokratie Jetzt and the Initiative Frieden und Menschenrechte. It received 2.9% of the vote in the 1990 Volkskammer elections. For the first all-German elections it formed a joint list with the East German Green Party. It was this coalition that merged with the West German Green Party in 1993.
On 7 February 1990, the Neue Forum ("New Forum"), the Initiative Frieden und Menschenrechte ("Peace and Human Rights Initiative") and Demokratie Jetzt ("Democracy Now") groups agreed upon the creation of the strategic partnership Bündnis 90 ("Alliance '90") for the German Volkskammer elections. On 18 March 1990, in the next and final free election of the former East Germany, the electoral alliance received 2.9% of the vote, thus securing 12 seats. By far the best result for Alliance '90 was in constituency of Berlin with 6.3%. In the remaining constituencies results ranged from 1.6% in Neubrandenburg to 3.8% in Potsdam. Together with the eight electees from the "Green Party in the GDR", they created the Fraktion Bündnis 90/Grüne ("Alliance '90/Greens Party").
In the East German Landtag election on 14 October 1990 the differently-comprised electoral alliances made their entry into every Landtag except Mecklenburg-Vorpommern, where the Neue Forum did not participate in the alliance. In Brandenburg, the three civic groups of the Bündnis 90 took office alone. In other states, the Greens also successfully took part in the electoral alliances. In Brandenburg from 1990 until 1994, Bündnis 90 formed part of a traffic light coalition with the Social Democrats and Free Democrats.
In the 12th Bundestag election on 2 December 1990, the first after the German reunification, 6.1% of voters in the Eastern electoral area (1.2% across Germany) cast their Zweitstimme (the vote for a party, as opposed to for a person) for the group Bündnis 90/Grüne - BürgerInnenbewegung ("Alliance '90/Greens - Citizens' Movement"), that entered into the German Bundestag with eight East German electees: Klaus-Dieter Feige, Ingrid Köppe, Gerd Poppe, Christina Schenk, Werner Schulz, Wolfgang Ullmann, Konrad Weiß and Vera Wollenberger. Werner Schultz took over the function of Speaker of the Bundestag group, which he held for the entirety of the legislative period. Its West German partners, the Greens, fell short of election to the parliament.
On 21 September 1991, the party Bündnis 90 was founded, which brought together parts of the Neue Forum, Demokratie Jetzt and the Initiative Frieden und Menschenrechte. On 14 May 1993 came the agreement create the union of Bündnis 90/Die Grünen with the Greens which had been a cross-German party since the end of 1990.
One part of the Brandenburg state alliance advocated against a unification with the Greens, including Matthias Platzeck, Günter Nooke, Ute Platzeck, Peter Schüler, Manfred Kruczek and Gerd Gebhardt. However, they were unsuccessful in their case and founded the BürgerBündnis ("Citizens' Alliance"), headed by Günter Nooke, Matthias Platzeck und Wolfgang Pohl.
The party Bündnis 90/Die Grünen in Saxony had already been established on 27 September 1991, one and a half years before the unification at federal level.