"Mass migration" refers to a large number of people moving from one place to another, usually from one country to another, within a relatively short period of time.
Sentences with «mass migration»
That includes not only conflict, but also mass migration of people. (bitsofscience.org)
His research focuses on cultural psychology and psychological anthropology, with an emphasis on mass migration, globalization, and education. (reimaginingmigration.org)
So, if we get climate change wrong there is a very real danger we shall see levels of mass migration as yet unparalleled. (politics.co.uk)