The word Muscovy (also known as Moscovia) emerged between the 15th and 16th centuries in notes of European writers and spread relatively quickly. It can be observed in various texts and geographical maps. Even though the term Muscovy was never used domestically, phrases like “the Moscow state”, “the Moscow Tsardom”, and “the Moscow lands” were accepted inside Russia in the 16th century and especially in the 17th century. They were used as synonyms for the “Russian state”.
One theory suggests that Muscovy is a pejorative term invented by Europeans (primarily Poles) to discredit Russia. In reality, people who wrote and spoke about “the Moscow state” were quite ardently “pro-Russia”.