Minor Moscow Princedom was doomed to head the struggle against The Golden Horde in the middle of XIII century, then, oppose the Lithuanian threat in the Eastern Europe, overcome feudal division of Russia and became a dominant political power. Moscow rise and its gradual transformation into the national center of integration of Russian lands cannot be explained merely by its favourable geographical position. The initial territory of Moscow Princedom was not very large, even after joining of Kolomna and Mozhaisk.
The first Moscow rulers succeeded not only to seize the Grand Dukes' Throne (other princes would manage it too), but also preserve it despite of all princely internecine strifes and intrigues in the Khan's headquarters.
Hegemony of Moscow in Northeast Russia laid the political foundation of formation of a single Russian State. Its creation was not sufficiently prepared economically as it was in the centralized states of the Western Europe. Prospering cities and trading intercourse were not the cementing basis on which the construction of the single national state was carried out. The less spontaneous economic forces played in the unifying process, the more the role of military-political force was.
Noting this feature P.N. Milyukov called Muscovy 'the Military-National State', which he figuratively compared to a military camp. Association of Russian Lands around Moscow occurred above all under the influence of foreign factors - necessity of national independence from The Golden Horde and deliverance of a part of Russian territories from Lithuanian Rule. In 1380 The Grand Duke of The Whole Russia (the Moscow rulers' official title) Dmitry Ivanovich defeated the army of The Golden Horde. By that time Moscow Princedom was already the largest and strongest among all Russian Lands. In 1480 (the rule of Ivan III) it stopped to render tribute to the Khans of The Golden Horde. The Great Moscow Princedom had 430 thousand square kilometers and approximately 3 million people by the year of 1462; during the rule of Ivan III and Vasily III the territory increased 6 times, and the population - twice.
Muscovy preponderance over the Lithuanian State was formed between XV and XVI centuries. This preponderance was not caused only by military power, but also was due to yearning of the Eastern Slavs to rejoin Russian National State.
So, this was the time of formation of a single Russian State. But this process included just a part of the old Russian lands, only the princedoms, which had been under the Golden Horde Rule. Association of the lands around Moscow was gradual, stage-by-stage liberation (struggle for independence) from the Golden Horde Yoke. Thus, integration of Russian Princedoms into a single National State was based less on economic and cultural relationship and more on military power of The Moscow Great Princedom.
Moscow State Formation
Russian State in XVI century
Restoration after "Distemper"