A question that seems to be unanswerable

If you really meant to say "European," Moscow and the historically noteworthy regions of Russia are all located in Europe, even though most of the territory of the modern nation of Russia lies in Asia. Russian is universally regarded not only as a European language, but since WWII as one of the most important.

Although geologically Afro-Eurasia is a single continent with no discontinuities created by bodies of water, geographers regard the European Peninsula--the portion of the continent northwest of the Ural Mountains, the Ural River, the Caspian Sea, the Caucasus Mountains and the Black Sea--as a separate continent, anthropologically, ecologically, historically and politically. Geographers count seven continents versus the geologists' four: Afro-Eurasia, America, Australia and Antarctica. Note that a great many islands, e.g., Britannia, Ireland, Iceland, Sicily, Corsica, Majorca and Malta, are colloquially and politically, but imprecisely, considered as parts of "Europe."

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But I didn't say "European," I said "Indo-European," which is a linguistic term.

Russian is a Slavic language, closely related to Czech, Slovak, Polish, Ukrainian, Belarus, Bulgarian, Serbo-Croatian, Slovene, etc. These are all descended from a single Proto-Slavic language, whose date of origin is difficult to pinpoint precisely but was sometime between 200BCE and 600CE in the original homeland of the Slavic tribes, very roughly the region stretching from Thessaloniki to Novgorod.

Most linguists agree that the Slavic languages fall within a larger Balto-Slavic group. The only living Baltic languages are Latvian and Lithuanian; Prussian became extinct very recently and is well documented. Reconstruction of a Proto-Balto-Slavic ancestral language is difficult and its origin has not been dated.

Many linguists place Balto-Slavic into an Eastern Branch of the Indo-European language family, which also includes Albanian, Armenian and the huge Indo-Iranian group of Indian and Persian languages such as Farsi, Pashto, Hindi/Urdu, Punjabi and Bengali. This is a controversial grouping whose historical timeline is virtually impossible to determine. The defining distinction between the hypothetical Eastern and Western Branches of Indo-European is the evolution of a single phoneme. In the Eastern or "Satem" languages, the word for "hundred" begins with S: Russian sto, Sanskrit satem. In the Western or "Kentum" languages it begins with K (often spelled C): Latin centum, Greek hekaton, Irish cead. Note that K is a fragile phoneme that has continued to degrade in diverse ways, from the TH in Spanish cien to the S in French cien to the CH in Italian cento to the H in English hundred.

The Proto-Indo-European language has been undergoing reconstruction for more than a century, and we have isolated many of its words, sounds, grammatical inflections and elements of syntax. The word for "hundred," for example, was kmtom. "Hand" was men-, cf. Latin manus, English "manual."

The Proto-Indo-European language seems to go back to some time between 6000 and 4000BCE. Its initial breakup into branches or groups (Greek, Indo-Iranian and a precursor of Celtic and the other western European languages) was complete by 2500BCE.

The homeland or Urheimat (a fancy German word) of the original Indo-European tribe(s) is not easy to locate. Perhaps the most popular (but hardly unanimous) hypothesis is that it was on the Pontic Steppe, the southeastern corner of Europe west of the Urals and north of the Black Sea. This is (with much greater certainty) also the region where the domestication of the horse took place around 3500BCE, one of the most important technologies in the development of human culture because of the mobility it provided. Without the horse there would have been little reason to invent the wheel.