The purpose of the article is to reveal the features of the study of relict Paleo-Balkan languages in their connection with other Indo-European languages in linguistics of the second half of the XIX century – the beginning of the XXI century. It is noted that when identifying a group of Paleo-Balkan languages, a single criterion has not yet been clearly established: both areal and genetic principles are involved. At the same time the material of Paleo-Balkan languages is not fully taken into account in the genealogical classification of Indo-European languages; if Thracian, Phrygian, and Illyrian languages are included in this classification as separate groups, then the place of old Macedonian, “Pelasgian”, and other Paleo-Balkan languages in the classification is not defined. In addition, the traditional genealogical classification does not take into account the special proximity of Paleo-Balkan languages to Armenian, Albanian and Ancient Greek. The discovery and study of Paleo-Balkan languages are briefly described. The connections of Paleo-Balkan languages with Albanian, Armenian, Ancient Greek, Hittite, Luvian, Baltic, Germanic, Slavic and Indo-Iranian languages are revealed. The author of the article focuses on the fact that Paleo-Balkan languages are mainly reconstructed at the phonological, lexical, derivational levels (to a lesser extent – at the morphological and syntactic levels), although due to the limited and uneven corresponding data, such reconstruction is also limited, and in some cases contradictory. From the point of view of Indo-Europeanists, lexical elements of Paleo-Balkan origin are recorded in modern Albanian, Greek, Bulgarian, Romanian and Armenian. The article emphasizes that Paleo-Balcanistics provided significant factual material important for substrate theory and contributed to the development of the linguistic stratigraphy method.

The task of the article is to reveal the peculiarities of the study of “dead” Tocharian languages in their connection with other Indo-European languages at all levels of the language system in linguistics of the XIX — early XXI centuries. It is noted that the discovery and study of Tocharian A and Tocharian B, qualified as centum languages, played an important role in improvement of the genealogical classification of Indo-European languages. The study of Tocharian languages are briefly described in the studios of W. Krause, W. Thomas, A. J. van Windekens, D. Q. Adams, V. V. Ivanov, T. V. Gamkrelidze, S. A. Burlak, etc. The connections of Tocharian A and Tocharian B with Celtic, Italiс, Germanic, Baltic, Slavic, Thracian-Phrygian, Hittite, Armenian languages are revealed. There is also traced Tocharian non-Indo-European influence of agglutinative language (W. Krause). The author of the article gives a brief description of the Tocharian languages at the phonological, lexical, morphological and syntactic levels. The archaic features of the Indo-European dictionary have been preserved in the Tocharian languages. It is concluded that the place of Tocharian languages among other Indo-European languages has not yet been clearly defined. It is necessary to emphasize the importance of the facts of Tocharian A and Tocharian B for researchers of other groups of Indo-European languages, to review a lot of statements of Indo-European studies.