The North Africans didn't go to Belgium seeking refuge. The Belgians actively recruited them as laborers and invited them into the country. You analogy to the Romans and Goths is flawed.
I'm not trying to downplay the problems caused by the recent flood of immigration to Europe, but the terror attacks in France and these in Brussels were carried out by born-and-bred Frenchmen and Belgians.
The central analogy was made to fact that the Emperor believed letting in barbarians would benefit the Empire by providing troops and taxes. Your example was of modern empires that believed letting in Muslims would be beneficial by providing cheap labor.
Both then and now, time has more and more swamped whatever short term benefits there were with disastrous costs that threaten the survivability of the West today and Rome of antiquity.
And the reason was that in both cases the "Rulers" (and you) refuse to see the hostile intentions of those they allowed in their country - and that is true today whether they be classified as migrants, refugees, guest-workers or whatever.
The irony of the Goths seeking refuge from the same Huns they soon allied with to attack their host country - just as Muslim refugees from Muslim violence abroad are joining with foreign Jihadi to attack their host countries - is just an additional analogy.
As Roman history portents, we are only beginning to see the disastrous results.
Forget the quick unthinking defensive reply. Try thinking about the fact presented to you and the tragic consequence of so many like you being so wrong.
I missed that whopper!
Look up "bred" and you'll find "reared in a specified environment or way."
Have you been so brainwashed by PC media that you think Muslims bred by Muslim families in Muslim enclaves of Belgium/France are being reared in Belgian/Frence environments and ways?
As for irrelevance of place of birth in allegiance, I dealt with that in my initial post concerning barbarians born on Roman soil joining across several generations to topple the Roman empire - in spite of where they were born. [Follow the time line I provided!]