The coat of arms of Germany is a symbol of Germany; the coat of arms feature an eagle. The colors of the coat of arms are similar to those of the flag of Germany (black, red and gold). It is the one of the oldest extant state symbols of Europe and is one of the oldest insignia in the world. Moreover, its history as an emblem began even earlier. To the Germanic tribes, the eagle was the bird of the god Odin. The Romans reserved aquiline imagery for only the most revered beings; namely, the supreme god and the emperor; and it served as a metaphor of invincibility. Later, through its rei rock eagle (adler), referred to in German as the Reichsadler, on German soil probably date back to the time of Charlemagne (742-814). Around the year 1200 the black eagle icon on a gold field was generally recognised as the imperial coat of arms. In 1433 the double-headed eagle was adopted for the first time by the Holy Roman Emperor Sigismund. Since then the double-headed eagle came to be used as the symbol of the Roman-German emperor, and hence as the coat of arms of the Holy Roman Empire of the German Nation. From the middle of the 15th century onwards, the respective emperors put the emblem of their dynasty on the eagle's chest. After the end of the Holy Roman Empire of the German Nation in 1806, a German state and a unified state emblem ceased to exist. In 1815, a German Confederation (Bund) of 39 loosely-united German states was founded on the territory of the former German empire. Until 1848, the confederation did not have a coat of arms of its own. The Federal Diet (Bundestag) meeting at Frankfurt am Main used a seal which carried the emblem of the Austrian Empire, since Austria had taken over the union's leadership. It showed a black, double-headed eagle, which Austria had adopted just before the dissolution of the Holy Roman Empire of the German Nation.