The Principality of Moscow or Grand Duchy of Moscow, also known simply as Muscovy, was a principality of the Late Middle Ages centered on Moscow. It eventually evolved into the Tsardom of Russia in the early modern period. The princes of Moscow were descendants of the first prince Daniel, referred to in modern historiography as the Daniilovichi, a branch of the Rurikids.

Russian is an East Slavic language, spoken primarily in Russia. It is the native language of the Russians and belongs to the Indo-European language family. It is one of four living East Slavic languages, and is also a part of the larger Balto-Slavic languages. It was the de facto and de jure official language of the former Soviet Union. Russian has remained an official language in independent Russia, Belarus, Kazakhstan, Kyrgyzstan, and Tajikistan, and is still commonly used as a lingua franca in Ukraine, Moldova, the Caucasus, Central Asia, and to a lesser extent in the Baltic states and Israel.