Traditional Belarussian folklore (songs sung at harvest, in particular) reveal layers of melodic mono- and polilexis. Respectively, those create special Jones - the isolates of the melodic relics that have been preserved by the original folk living in the area. There are also other zones - of the mixed, contaminational lexicon. Thus, the directions of migration and contact places of the three primordial areas of harvest-melodic types. Research in and on the zones of mixed lexicon brings abort a question of appearance or non-appearance signs of assimilation and signs of inter-ethnic 'assimilation-resistance' in the musical-singing language. The authoress presents a variety of cultural-lexical cross-interference and interaction of the Uhr-Belarus ethnic groups. She defines co-relations, Baltico-Slavonic 'shares' in formulation of singing-melodiaic language of the Belarussians. Ad-stratic feature of the singing-melodiaic language is a result and, obviously, an evidence for the tri-ethnic composition of the old harvest-singing Belarusisan culture. The melolexical data, namely, directionality and isomels' density, existence of areas where 'archaisms are conserved ' and the existence of touch-contact zones - can be preliminarily correlated in terms of stratigraphy, and thus the time correlation is also possible, with the following: (1) archaeological cultures (Poles'e, Sozh and Neman-Dvina melolexes - and the culture zones of Milograd, Zarubinets and the one of the Hatched Ceramics culture); (2) linguo-dialectological division (entire Neman and Sozh izomels, including the migration current , - vs. the zone of central-Belarussian dialects ); (3) ethnographic phenomena (female costume). .