This is why most American Silver antiques made ca 1860s – 1900 are termed “Coin Silver” because the silver content of such items was the same as in the recipe used in making actual currency coins at the US National Mint.
Even so, for 600 years (c.400-1000 CE) Europe was a cultural backwater.
In particular, the alleged establishment by "Oleg" in 882 of the principality of Kiev should be treated with caution.
Nevertheless, the historical existence of Ruriks supposed son Igor, and Igors son Sviatoslav, is corroborated by the The arrival of Scandinavian traders in the territories which later developed into "Rus" should be seen in the context of the Khazar and Pecheneg 9th and 10th century occupations of the area, which would appear to have left little opportunity for the establishment of powerful principalities by Scandinavian newcomers, at least in the open plain lands.
The author suggests that Vsevolod adopted this title to strengthen the separation of the principality of Vladimir from Kiev and also to place himself over the lesser princes of the Russian north.
Use of the title by Vladimirs descendants was confirmed when Prince Iaroslav Vsevolodich received the title "Grand Prince of Vladimir" from Khan Batu of the Golden Horde in 1243, in return for swearing allegiance.