Liberal derision re: anti-immigrant behavior occasionally drops the following snide argument: Unless you're an American Indian, you have no right whatsoever to complain.
A POX ON PEOPLE WHO SAY THIS!!! This is a specious argument that assumes that American Indians (the PC term "Native American" implies this) are a monolithic group and that, more importantly, they "got here first." The fact of the matter is that no one really knows who got here first! The sum total of what we now know as American Indians are the descendants of successive waves (experts still debate exactly how many and when) of pre-historical migration who, by the time Columbus made his landing, spoke hundreds of different languages. As such, most Native Americans are actually descendants of people who, like the immigrants of the more recent times, either displaced, intermarried with, warred with, and/or lived alongside other cultures. (Never mind that the the first wave of immigration from Asia to the Americas happened so damn long ago that we are all, EVERY ONE OF US, descendants of those original immigrants!)
Therefore, far better to structure pro-immigration arguments this way: The Americas have been a multicultural milieu for the great bulk of human history. What's stopping us now?