> these countries have not invited 1 million+ people from a dramatically different(read: backwards) cultures

Sweden's had quite the spread from backwards nations to reach that 1 million (2010 - 2020 inclusive):

* Poland 47,940

* Somalia 46,044

* Germany 26,945

* Finland 26,521

* Denmark 21,792

* United Kingdom 21,285

* Norway 21,265

* United States 19,378

etc. ( https://en.wikipedia.org/wiki/Immigration_to_Sweden#Contempo... )

With the largest number, 177,154 from Syria - more wartorn and shredded by decades of totalitarian dictatorship than intrinsically 'backwards'.