The treatise proposes a hypothesis about the change of importance of individuals’ ethnic belonging for the formation of collective identities, referring to this phenomenon as “amplitudes of the importance of ethnicity”. The research is based mainly on the ethno-symbolist paradigm of elucidating the formation of modern nations. Historiography has already noticed the “amplitudes of the importance of ethnicity”; however, this phenomenon is yet to be systematically researched. This treatise thus represents an overview of general European trends of the importance of ethnicity in arbitrarily selected historical periods. The phenomena of (proto) nationalism coincide with the “amplitudes of the importance of ethnicity” on the timeline of long-term history