Krievi - Krīvi - Venäläiset - Russians - Московити

Ethnic Russians (in English), Krievi (in Latvian), Krīvi (in Latgalian), Росіяни (in Ukrainian), Rosjanie (in Polish), Venälaižed (in Veps), Venelased (in Estonian), Vindläseq (in Vöro). Russia (English) but Venäma in Estonian and Krievija in Latvian (bcs of Kriviches tribe) and Krīvija in Latgalian. Kriv was legendary Baltic (!) forefather of Kriviches, some sort of a heathen "high priest". According to a recent genetic study, namely Baltic Lithuanians happened to be the closest genetic relatives of central Russians (Orel, Bryansk, Smolensk, Ryazan, Ivanovo oblasts - lands of Viatiaches tribe. Viatiches practised Baltic burials. Besides that they abosrbed Baltic Golyad) - see video on genetics of Russians.

Modern Russian ethnicity got formed out of several tribes. Several Slavic tribes, mainly Kriviches (northern and western Russians, from Kriv, Baltic forefather), Viatiches (south and central Russians / Slavs with Baltic substratum), Baltic tribe of East Galindians (Golyad of Moscow region), plus a number of Finnic tribes (Merians, Vepses, Komi-Permians, Muroma and Erzyans (Mordvins). European Russians are mainly Balto-Slavs with significant Finnic admixture (especially in the north). I would say that Viatiches (Slavic tribe with Baltic element) played the crucial role in the formation of Russian ethnos - http://en.wikipedia.org/wiki/Vyatichi

Viatichi - Kaluga (around Kaluga), east & south Moscow (along Moscow river) region, north Orel, north Ryazan region

Meria (Finns) - Ivanovo, Yaroslavl, Tver, and Kostroma regions (mixed with Kriviches)

Kriviches (many believe it is an old Baltic tribe) - Pskov, Smolensk, Yaroslavl, Tver, Ivanovo regions (mixed with Meria)

Golyad (East Galindians) - pure Balts - northern Kaluga region (around Borovsk and Omninsk, basin of Protva river) and western Moscow region (Vereya, Naro-Fominsk)

Radimichi - around city of Briansk

Novgorod Slovenes (spoke dialect similiar to Polish) - Novgorod, St. Petersburg regions (mixed with Veps / Ves tribe there). Some say Slovenes were a separate ethnicty from Muscovites (Pure Muscovites = Viatiches+Galinidians and some Merians). Novgorod Slovenes+Vepses (Finns) produced Pomors (northernmost Russians of Arkhangelsk & White Sea coast). Pomor shirt emroidery is identic to Veps.

Center of Viatiches tribe was in Korno (Kornoye, Mosalsk district of Kaluga province).
Chronicle says that Viatko, progenitor of Viatiches came from Poland. Viatiches, unlike other Slavs, had Baltic burials and jewellery (they have built up on some Baltic substrathus).

Vantit (Vait) - Arabic name for the land of Viatiches (original Russians). Viatichia would be more fair and distinctive ethnic name for Russia.

Note that the name Russia / Russians originally was just a political & religious term and didnt have any ethnic or tribal connotation. It was brought by the Viking sailors and first implied Maritime Swedes (Roden) - Ruotsi is Sweden in Finnish), then it served as uniting term for medieval Ukrainian tribes and people (Kyivan Rus state as Kyiv was the center of Viking Rurikide dynasty), then it was adopted as official name for Muscovite state (since the early 18th century) becoming uniting term for the tribes centered around Moscow, what we understand as modern ethnic Russians. Its similar to political terms Rome and Romans, that was transplanted from one people to another (Ancient Rome and Romans, then Romance people, Romeiko - Byzantine Greeks, Romania and Romanians etc).
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Ukrainians consists of completely different tribes (Derevlians, White Croats, Dulibes (Volhynians), Siverians which have nothing to do with modern ethnic Russians (Muscovites) and what is today understood as Russia (former Muscovy). Totally different folk costumes, patterns, embroidery, culture, language, genetics etc.
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Belarusians likewise consist of different tribes (Drehoviches + Polotsk Kriviches and some Volhynians) that are very different from Viatiches tribe (progenitor Russian tribe). Though northern Belarusians belonged to same Kriviches tribes, but this tribe had 2 branches that developed separately - northern Pskov Kriviches (in Russia) and southern - Polostk & Smolensk Kriviches (northern and eastern Belarusians). These werent the same as they lived in great distance. Baltokrievija is Latvian name for Belarus. In general Russians and Belarusians, unlike Ukrainian, have significant Baltic element (hence Baltic akanie (pronouncing o as a) in their languages, unknown in Ukrainian. Ethnically Ukrainians are more close to south Belarusians, Lusatian Serbs (ancient Croats), south Poles, Slovaks, and Czechs (all have Scytho-Sarmatian h sound instead of Balto-Slavic g)
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Видео Krievi - Krīvi - Venäläiset - Russians - Московити канала PilgrimX