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.
Slavic languages
The Slavic languages, also known as the Slavonic languages, are Indo-European languages spoken primarily by the Slavic peoples or their descendants. They are thought to descend from a proto-language called Proto-Slavic, spoken during the Early Middle Ages, which in turn is thought to have descended from the earlier Proto-Balto-Slavic language, linking the Slavic languages to the Baltic languages in a Balto-Slavic group within the Indo-European family.

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
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Slavic languages [SEP] Introduction
In addition, Aleksandr Dulichenko recognizes a number of Slavic microlanguages: both isolated ethnolects and peripheral dialects of more well-established Slavic languages. The current geographic distribution of natively spoken Slavic languages includes Southern Europe, Central Europe, the Balkans, Eastern Europe, and all of the territory of Russia, which includes northern and north-central Asia (though many minority languages of Russia are also still spoken). Furthermore, the diasporas of many Slavic peoples have established isolated minorities of speakers of their languages all over the world. The number of speakers of all Slavic languages together was estimated to be 315 million at the turn of the twenty-first century.