ENThe invention of ethnographic regions of Belarus and Lithuania as tools of scientific classification and interpretation of territorial variants of ethnic culture is compared. The exceptional importance of socially relevant markers of territorial identity / difference for the successful construction of an ethnographic region in both scientific and broad public discourse is shown. The example of the historical Vilnius region demonstrates how ethnically heterogeneous border areas are integrated into national projects of ethnographic regions as a result of state and territorial changes. Keywords: ethnic culture, scientific classification, ethnographic region, categorization, identification, Belarus, Lithuania, comparative studies.