The "Duke of Moscow" refers to the title held by the rulers of the Grand Duchy of Moscow, which emerged in the late 13th century. This principality played a crucial role in the unification of Russian lands and the eventual rise of the Tsardom of Russia. The title was held by notable figures such as Ivan III, who expanded Moscow's territory and influence. The Duke of Moscow was instrumental in establishing Moscow as a political and cultural center. The title eventually evolved into the Tsar of Russia, marking the transition from a duchy to a more centralized monarchy. This shift laid the groundwork for the future Russian Empire.