There were no foreign nations, foreign or otherwise, at this time.
Descendants of Ham, Shem & Japheth immigrated to other places.
Similarly, there were no other peoples or nations when Ham, Shem & Japheth immigrated.
Noah & descendants immigrated to various places.
Noah & descendants would have been the genesis of tribes and nations following the flood. There was an entire unpopulated world for Noah descendants to occupy. There was no immigration as we understand it today.
Scriptures that apply to illegal immigration.
"Let every soul be subject to the governing authorities. For there is no authority except from God, and the authorities that exist are appointed by God." - Romans 13:1
And Jesus said to them, “Render to Caesar the things that are Caesar’s, and to God the things that are God’s.” -Mark 12:17
This is the real operative Scripture text. The civil law should be obeyed by everyone as long as it doesn't command a person to sin.
[guilty look] Yes, I sometimes speed on the interstate. I'm just trying to stay with traffic for safety's sake, officer. Truly I am.
With my Amish background, libertarian tilt & Christian belier, it is hard for me to conceive of my life, my redisdence, belonging to Ceasar. My taxes yes... but me..No!