The Hohenzollern dynasty is a prominent royal family that originated in the 11th century in what is now Germany. They played a significant role in European history, particularly in the formation of the Kingdom of Prussia and later the German Empire. The dynasty produced several notable rulers, including Frederick the Great, who expanded Prussia's territory and influence. The Hohenzollerns were divided into two main branches: the Swabian branch, which ruled over Swabia, and the Brandenburg branch, which became the ruling family of Prussia. The dynasty's reign ended after World War I when the last German Emperor, Wilhelm II, abdicated, leading to the establishment of the Weimar Republic.