I listened this morning to an interview with Michael Ignatieff. He was mostly talking about the Hungarian Prime Minister Viktor Orbán.
At some point (14:55 in the podcast (in French)), while he was discussing about the roots of the current anti-immigration political stance of the country, he mentioned that
There was in 2015 something unforgettable: one million of immigrants arrived within a week (...)
Hungary population is about 10 million, so one million is certainly not a planned arrival. Why did this happen? Is it because the country was open and not ready to close borders? Or because it expected less? Or something else?