Question: When did east Germany and Wolfgang Rott's country of citizenship unite?

full_context: Document 1: Unification of Germany: The unification of Germany into a politically and administratively integrated nation state officially occurred on 18 January 1871, in the Hall of Mirrors at the Palace of Versailles in France. Princes of the German states, excluding Austria, gathered there to proclaim Wilhelm I of Prussia as German Emperor after the French capitulation in the Franco - Prussian War. Unofficially, the de facto transition of most of the German - speaking populations into a federated organization of states had been developing for some time through alliances formal and informal between princely rulers -- but in fits and starts; self - interests of the various parties hampered the process over nearly a century of autocratic experimentation, beginning in the era of the Napoleonic Wars, which saw the dissolution of the Holy Roman Empire of the German Nation (1806), and the subsequent rise of German nationalism.
Document 2: Max Weinhold: Max Weinhold (born April 30, 1982 in Munich) is a field hockey player from Germany who plays in goal. He was a member of the Men's National Team that won the gold medal at the 2008 Summer Olympics. He was also chosen to represent his country in the London 2012 Summer Olympic Games where Germany again won gold.
Document 3: History of Germany (1945–1990): The intended governing body of Germany was called the Allied Control Council. The commanders - in - chief exercised supreme authority in their respective zones and acted in concert on questions affecting the whole country. Berlin, which lay in the Soviet (eastern) sector, was also divided into four sectors with the Western sectors later becoming West Berlin and the Soviet sector becoming East Berlin, capital of East Germany.
Document 4: Berlin Wall: In 1989 a series of revolutions in nearby Eastern Bloc countries -- Poland and Hungary in particular -- caused a chain reaction in East Germany that ultimately resulted in the demise of the Wall. After several weeks of civil unrest, the East German government announced on 9 November 1989 that all GDR citizens could visit West Germany and West Berlin. Crowds of East Germans crossed and climbed onto the Wall, joined by West Germans on the other side in a celebratory atmosphere. Over the next few weeks, euphoric people and souvenir hunters chipped away parts of the Wall; the governments later used industrial equipment to remove most of what was left. The ``fall of the Berlin Wall ''paved the way for German reunification, which formally took place on 3 October 1990.
Document 5: Oldřich Rott: Oldřich Rott (born 26 May 1951) is a former football midfielder from Czechoslovakia. He was a member of the national team that won the gold medal at the 1980 Summer Olympics in Moscow. Rott obtained a total number of three caps for his native country, between 1978-05-17 and 1979-03-14.
Document 6: Christiane Krause: She competed for West Germany in the 1972 Summer Olympics held in Munich, Germany in the 4 x 100 metres where she won the gold medal with her team mates Ingrid Becker, Annegret Richter and Heide Rosendahl.
Document 7: Territorial evolution of Germany: The territorial changes of Germany include all changes in the borders and territory of Germany from its formation in 1871 to the present. Modern Germany was formed in 1871 when Otto von Bismarck unified most of the German states, with the notable exception of Austria, into the German Empire. After the First World War, Germany lost about 10% of its territory to its neighbours and the Weimar Republic was formed. This republic included territories to the east of today's German borders.
Document 8: Dresden: Since German reunification in 1990 Dresden is again a cultural, educational and political centre of Germany and Europe. The Dresden University of Technology is one of the 10 largest universities in Germany and part of the German Universities Excellence Initiative. The economy of Dresden and its agglomeration is one of the most dynamic in Germany and ranks first in Saxony.  It is dominated by high-tech branches, often called “Silicon Saxony”. The city is also one of the most visited in Germany with 4.3 million overnight stays per year. The royal buildings are among the most impressive buildings in Europe. Main sights are also the nearby National Park of Saxon Switzerland, the Ore Mountains and the countryside around Elbe Valley and Moritzburg Castle. The most prominent building in the city of Dresden is the Frauenkirche. Built in the 18th century, the church was destroyed during World War II. The remaining ruins were left for 50 years as a war memorial, before being rebuilt between 1994 and 2005.
Document 9: Germany: After Germany surrendered, the Allies partitioned Berlin and Germany's remaining territory into four military occupation zones. The western sectors, controlled by France, the United Kingdom, and the United States, were merged on 23 May 1949 to form the Federal Republic of Germany (Bundesrepublik Deutschland); on 7 October 1949, the Soviet Zone became the German Democratic Republic (Deutsche Demokratische Republik). They were informally known as West Germany and East Germany. East Germany selected East Berlin as its capital, while West Germany chose Bonn as a provisional capital, to emphasize its stance that the two - state solution was an artificial and temporary status quo.
Document 10: Wolfgang Güldenpfennig: Wolfgang Güldenpfennig (born 20 December 1951) is a retired East German rower who competed at the 1972 and 1976 Summer Olympics. In 1972 he won a bronze medal in the single sculls event, whereas in 1976 he became Olympic champion in the quadruple sculls. Güldenpfennig won two world titles in the quadruple sculls, in 1975 and 1977, as well as a European bronze medal in the single sculls in 1973. After retiring from competitions he worked as a rowing coach, training Karl-Heinz Bußert, Uwe Heppner, Uwe Mund and Martin Winter.
Document 11: Wilfried Gröbner: Wilfried Gröbner (born 18 December 1949) is a German former footballer and coach who was part of East Germany's gold medal-winning team at the 1976 Olympics.
Document 12: Peter Kraus (field hockey): Peter Kraus (born 27 June 1941 in Rüsselsheim) is a former field hockey player from Germany, who was a member of the West German squad that won the gold medal at the 1972 Summer Olympics in Munich.
Document 13: States of Germany: After the Nazi Party seized power in January 1933, the Länder increasingly lost importance. They became administrative regions of a centralised country. Three changes are of particular note: on January 1, 1934, Mecklenburg-Schwerin was united with the neighbouring Mecklenburg-Strelitz; and, by the Greater Hamburg Act (Groß-Hamburg-Gesetz), from April 1, 1937, the area of the city-state was extended, while Lübeck lost its independence and became part of the Prussian province of Schleswig-Holstein.
Document 14: German reunification: The German reunification (German: Deutsche Wiedervereinigung) was the process in 1990 in which the German Democratic Republic (GDR / DDR / East Germany) joined the Federal Republic of Germany (FRG / West Germany) to form the reunited nation of Germany, and when Berlin reunited into a single city, as provided by its then Grundgesetz constitution Article 23. The end of the unification process is officially referred to as German unity (German: Deutsche Einheit), celebrated on 3 October (German Unity Day) (German: Tag der deutschen Einheit). Following German reunification, Berlin was once again designated as the capital of united Germany.
Document 15: Wolfgang Rott: Wolfgang Rott (born on 28 November 1946) is a former field hockey player from West Germany, who was a member of the West-German team that won the golden medal at the 1972 Summer Olympics in Munich. He also competed at the 1968 and 1976 Olympic Games, where West Germany finished fourth and fifth. He played at club level for THC Mettmann.
ground_truth: 1990
sub_queries: Wolfgang Rott >> country of citizenship Answer: West Germany
when did east germany and West Germany unite Answer: 1990