how did it evolve?
In the 19th century, Russian influenced most literary Slavic languages by one means or another.
Slavic languages
The imposition of Old Church Slavonic on Orthodox Slavs was often at the expense of the vernacular. Says WB Lockwood, a prominent Indo-European linguist, "It (O.C.S) remained in use to modern times but was more and more influenced by the living, evolving languages, so that one distinguishes Bulgarian, Serbian, and Russian varieties. The use of such media hampered the development of the local languages for literary purposes, and when they do appear the first attempts are usually in an artificially mixed style." (148)

Lockwood also notes that these languages have "enriched" themselves by drawing on Church Slavonic for the vocabulary of abstract concepts. The situation in the Catholic countries, where Latin was more important, was different. The Polish Renaissance poet Jan Kochanowski and the Croatian Baroque writers of the 16th century all wrote in their respective vernaculars (though Polish itself had drawn amply on Latin in the same way Russian would eventually draw on Church Slavonic
who would call the sea of japan the east sea South Korea where is this sea? It is bordered by Japan, Korea (North and South) and Russia. where did the last mentioned place take its name from? The name "Russia" is derived from Rus', a medieval state populated mostly by the East Slavs. who are there people you mentioned at the end? The East Slavs are Slavic peoples speaking the East Slavic languages. how are they sourced? The few known facts come from archaeological digs, foreign travellers' accounts of the Rus' land, and linguistic comparative analyses of Slavic languages what are these languages? The Slavic languages, also known as the Slavonic languages, are Indo-European languages spoken primarily by the Slavic peoples or their descendants.
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Slavic languages [SEP] Evolution
The imposition of Old Church Slavonic on Orthodox Slavs was often at the expense of the vernacular. Says WB Lockwood, a prominent Indo-European linguist, "It (O.C.S) remained in use to modern times but was more and more influenced by the living, evolving languages, so that one distinguishes Bulgarian, Serbian, and Russian varieties. The use of such media hampered the development of the local languages for literary purposes, and when they do appear the first attempts are usually in an artificially mixed style." (148) Lockwood also notes that these languages have "enriched" themselves by drawing on Church Slavonic for the vocabulary of abstract concepts.