The Grand Duchy of Moscow, or Grand Principality of Moscow, was a late medieval Rus principality centered on Moscow and the predecessor state of the early modern Tsardom of Russia. The state originated with Daniel I, who inherited Moscow in 1283, eclipsing and it later annexed the Novgorod Republic in 1478 and the Grand Duchy of Tver in 1485. After the Mongol invasion of Rus, Muscovy was a vassal to the Mongol ruled Golden Horde until 1480. By his marriage to the niece of the last Byzantine emperor, he established Muscovy as the state of the Roman Empire. Ivans successor Vasili III also enjoyed success, gaining Smolensk from Lithuania in 1512. Vasilis son Ivan IV was an infant at his fathers death in 1533 and he was crowned in 1547, assuming the title of tsar together with the proclamation of Tsardom of Russia. As with many states the country had no particular official name. The Duke of Moscow or the Sovereign of Moscow were common short titles, in rivalry with other duchies Moscow dukes also designated themselves as the Grand Dukes, claiming a higher position in the hierarchy of Russian dukes. During the territorial growth and later acquisitions, the title became rather lengthy. Since the 14th century various Moscow dukes added of all Rus to their titles, after the title of Russian metropolitans, Dmitry Shemyaka was the first Moscow duke who minted coins with the title the Sovereign of all Rus. Under the Polish-Lithuanian influence the country began to be called Muscovy in Western Europe, the first appearances of the term were in an Italian document of 1500. Initially Moscovia was the Latinized name of the city of Moscow itself, not of the state, later it acquired its meaning and has been used alongside of the older name. The term Muscovy persisted in the West until the beginning of the 18th century and is used in historical contexts. When the Mongols invaded the lands of Kievan Rus in the 13th century, the first ruler of the principality of Moscow, Daniel I, was the youngest son of Alexander Nevsky of Vladimir-Suzdal. He started to expand his principality by seizing Kolomna and securing the bequest of Pereslavl-Zalessky to his family, daniels son Yuriy controlled the entire basin of the Moskva River and expanded westward by conquering Mozhaisk. He then forged an alliance with the overlord of the Rus principalities, Uzbeg Khan of the Golden Horde, the Khan allowed Yuriy to claim the title of Grand Duke of Vladimir-Suzdal, a position which allowed him to interfere in the affairs of the Novgorod Republic to the north-west. Yuriys successor, Ivan I, managed to retain the title of Grand Duke by cooperating closely with the Mongols and by collecting tribute and taxes from other Rus principalities on their behalf. This relationship enabled Ivan to gain regional ascendancy, particularly over Moscows chief rival, the city of Tver
The seal of Simeon the Proud (1340s), reads: "The seal of the Grand Duke Simeon of all Rus'"
Blaeu's map of Russia (1645), Moscovia is Moscow and the vicinities
During the reign of Daniel, Moscow was little more than a small timber fort in the forest of Central Rus'.