And the influence of tribal languages, lived side by side with the Baltic nations, to a greater or less apparent in the Baltic language group. Of the Iranian languages in the Baltic moved some hydronyms (about 20) of the Thracian-Illyrian language – about hundreds of names of languages, the German group was transferred also a sufficient number of hydronyms and place names. If we consider the connection of the Slavic languages from the Baltic, in contrast to relations with other languages, which are external to the Baltic languages, these bonds are affected internal to their side. In studying this issue are generally considered two positions on the nature of relations between the two languages in antiquity, which have radically different directions. Scientists who support the first position, convinced that there was a proto Baltic and Slavic groups, which explains their relationship. And those who hold the second position, argue that initially the two languages have a certain amount of distinct features. Say that some of the positions is not absolutely correct. Recently, a new assumption about the link between the Baltic and Slavic languages, the essence of which is development of Slavic languages as a later development of the outlying dialects of the Baltic languages.
So, from 20 to 5 century bc, Proto-Slavic language was represented by some Baltic dialects and perhaps that should be call the Balto-Slavic proto-language. There are different assumptions about the connection of the Slavic languages from the Baltic and to some extent the right may be considered, almost everything. And that such a relationship exists – is the undisputed fact, the evidence base is quite extensive. Returning to comparative historical studies of the Baltic languages, can be identified are common to all Baltic languages features in morphology, phonetics, word formation, syntax, the vocabulary of the language and phraseological units. However, the unity of the Baltic group of languages can be found, and not using the research in the above areas. They can be seen in As a whole group and by its synchronicity. When comparing the Baltic languages with other groups on linguistic typology, that is, their structural and functional properties, regardless of the nature genetic relationships between them, the integrity of the group in question does not cause any problems.