According to the Normanist theory, the name may originate from the tribe of Rus which may have been of Norman descent and inhabited the rivers of the region. In their Old Norse language they called this region Gardarike which meant "kingdom of cities". The theory states that the word "Rus'" was adopted by the Slavs from the Norse root roðr, in compounds roþs- (roths-), either directly or via the Finnish Ruotsi. This root is the same as the English row and may have referred to the fact that the Varangians mainly rowed down the East European waterways; cf. the Swedish region, Roslagen, which means "naval districts." On this Eastern Slavic land the Rus' warriors created a first polity, the Rus' Khaganate, which was formed alongside the trading route between Scandinavia and Greeks (Byzantium) and later evolved into Kievan Rus after the political center moved from Staraya Ladoga and Novgorod to the strategically comfortable Kiev.
The Anti-Normanist theory is based on the concept of the impossibility of the introduction of statehood from without, on the idea that the appearance of state is the stage of the internal development of society. Mikhail Lomonosov was considered the founder of this theory in the Russian historiography.
Furthermore, there are different points of view as to the origin of Varangians themselves. Scientists, who are normanists, consider them to be Scandinavians, while part of the anti-normanists, beginning from Lomonosov, consider them to be of the Western-Slavic origin. There are also intermediate versions of the localization - in Finland, Prussia, another part of the Baltic States. The problem of the ethnic belonging of Varangians is independent from a question of the appearance of statehood.
Contemporary science predominately believes in the point of view, according to which the rigid contrast “of normanist” and “of anti-normanist” theories is in many respects paralyzed; the prerequisites of age-old statehood in eastern Slavs were denied neither by Miller nor Shletserom nor by Karamzin, while an external (Scandinavian or other) origin of the ruling dynasty - sufficiently prevalent in the middle ages phenomenon, in no way proves the incapacity of people in the creation of state or, more specifically, the institute of monarchy.
Questions about whether Ryurik was the founder of the dynasty, the origin of Varangians, whether it was connected with the name Rus' and then the name of state Russia, continue to remain debatable in the contemporary domestic historical science. At the same time, Western historians as a whole follow the concept of Normanist theory.
The Kievan Rus had its cultural and political height in the 10th and 11th century and later disintegrated into many small principalities. The most powerful successor states were Vladimir-Suzdal, Halych-Volhynia and Novgorod Republic. The Mongol invasion of Rus devastated the north-eastern parts in 1237-1238 and the south western parts of Rus in 1239-1240. From this date on the fate of Rus lands began to diverge. The north-eastern parts stayed under the rule of Mongols and the Golden Horde for two more centuries while the western parts together with Kiev were conquered by Lithuania (see Battle on the Irpen' River) and Poland. This political development caused a certain cultural and linguistic split between Eastern Slavs which previously almost didn't exist. However, the Orthodox church which resided in Vladimir and later in Moscow remained a common unifying factor of Rus lands. In the Grand Duchy of Lithuania which had an Eastern Slavic majority of population as well as the official Slavic language the Orthodox Christians started to face persecution(citation needed) by the ruling Lithuanian elite in the second half of the XV century. A rivalry between the Grand Duchies of Moscow and Lithuania both of whom considered themselves as centers of Rus and legitimate successors of Kiev (Ivan III called himself the Grand Duke of all Rus) caused several wars and showed Muscovite overweight by the beginning of the 16th century. Lithuania was forced to seek help from Poland and the two states formed the Polish-Lithuanian Commonwealth where Poland began to play a dominant role promoting Catholic rule in the Western Rus(citation needed).
Russia managed to gradually roll back its opponent by the end of 18th century when Catherine the Great initiated the Partitions of Poland. By that time, all Rus lands were united under control of Saint-Petersburg, except Galicia which became part of Austria-Hungary.
The Greeks used to call the lands around Kiev Rossia Mikra (Rus in the narrow sense) and the entirety of all other lands Rossia Makra (Rus in the broader sense, Greater Rus). Later, this coined the terms Great Russia and Little Russia.