Wikipedia (en)
The Grand Duchy of Moscow (Russian: Великое княжество Московское, romanized: Velikoye knyazhestvo Moskovskoye), or simply Muscovy (from the Latin Moscovia), was a Rus' principality of the Late Middle Ages centered on Moscow, and the predecessor state of the Tsardom of Russia in the early modern period. It was ruled by a branch of the Rurik dynasty, which had reigned in Kievan Rus' since its foundation.
The state originated in 1263, when the prince of Vladimir-Suzdal Alexander Nevsky created the Grand Principality of Moscow as an appanage for his son Daniel I. Initially, Muscovy was a vassal state to the Golden Horde, paying the khans homage, tribute and troops to fight in their wars. Moscow eclipsed and eventually absorbed its parent duchy of Vladimir-Suzdal by the 1320s, and later annexed several neighbors including the Novgorod Republic in 1478 and the Principality of Tver in 1485. It remained a vassal state of the Golden Horde until 1480 following the Great Stand on the Ugra River, though there were frequent uprisings and several successful military campaigns against the Mongols, such as an uprising led by Dmitri Donskoy against the ruler of the Golden Horde, Mamai, in the Battle of Kulikovo in 1380.Ivan III further consolidated the state during his 43-year reign, campaigning against his major remaining rival power, the Grand Duchy of Lithuania, and by 1503 he had tripled the territory of his realm. Ivan's successor Vasili III also enjoyed military success, gaining Smolensk from Lithuania in 1512 and pushing Muscovy's borders to the Dnieper. Vasili's son Ivan IV (later known as Ivan the Terrible) was crowned in 1547, assuming the title of tsar together with the proclamation of the Tsardom of Russia (Russian: Царство Русcкое, Tsarstvo Russkoye).