ENThe term "diaspora of cataclysm" has been introduced to academic discourse by American sociologist Rogers Brubaker. The social phenomenon fulfilling the criteria of the "diaspora of cataclysm" accompanied the disintegration of multi-national states and empires – the Russian Empire under the Romanovs or the Habsburg Monarchy, and in modern times – the Soviet Union or Yugoslavia. As a result of a change in state borders the titular and dominant nation became a diaspora. It was nationalism that, as a rule, became a mechanism that secured the dominant position of a dominant nation. As a consequence of changes in state arrangement in the Vilnius Region and migrations in the 20th century, Belarusians, who constituted the indigenous population, became a national minority subjected to assimilation policy by subsequent regimes.