Introduction. The interest of world science in assessing the ethnic diversity of countries and regions predetermines the development of the concept of ethnocontact zones. To test new methods within the framework of the concept, there is a need to conduct research not only at the regional, but also at the intraregional levels. The purpose of the study is to classify the municipalities of Chuvashia, Tatarstan and Bashkortostan according to ethnic dynamics in the post-Soviet period using the methodology developed by the authors in accordance with the concept of ethno-contact zones. Materials and Methods. The empirical basis of the study is ethnic statistics at the level of municipalities of the republics based on the results of the population censuses of 1989, 2002 and 2010. The authorsʼ method of identifying the phases of development of ethnocontact zones, which was first applied at the municipal level, is presented. Results. The general trend of ethnic processes in the last decade of the 20th century was the titularization of the population of the republics (with the exception of Chuvashia), and in the first decade of the 21st century – detitularisation of the population (except for Tatarstan). The processes of titularisation and detitularisation at the level of municipalities are determined both by the general trend in the change in the share of the titular population of the republics, and by ethnogeographic features associated with the different proportion of titular peoples in municipalities, which is largely due to their central, semi-peripheral or peripheral position within the republics. Discussion and Conclusion. The spatial patterns of ethnic dynamics revealed in the course of the study, corresponding to certain phases of development of ethnocontact zones, make it possible to forecast ethnic processes at the intraregional level. However, such a forecast is possible only if the general trend of ethnic processes at the level of national formations is known. For this reason, the new task in the course of developing the concept of ethnocontact zones was to study the dynamics of ethnocontact zones on a regional scale over a long time interval, which will allow us to proceed to predicting the development of these ethnocontact zones in the medium and long term.