Russian nation was created by Russian climate and Russian blood.
Contrary to common misconception, Russians living on territory of Russian Federation are not of Slavic blood. The ancient inhabitants of Kiev’s principate were Slavic people, that’s true. When Moscow principality was created a few centuries later in the 14th century, its population was overwhelmingly Urgo-Finns. Descendants of Kiev’s genealogical tree, their princes were originally of Slavic blood. But when Kiev’s armies moved north with their small troops, they conquered enormous vast variety of Finnish tribes who lived on enormous territory of European Russia. Only aristocrats of Russia were originally Slavs. Simple folk were descendants of Finns. That is why it is practically no different between “Chuvash” and “Finn.” And that is why Serbs are so different from Russians. Because Serbs are Slavs.