1) There was no cohesive nation of Tribal Americans with borders or treaties (but which tribes were rife with internecine warfare, scalp hunting, child sacrifice, and other charming customs: they made themselves disunited and weak.)
2) There was no welfare state to entice and indulge the new arrivals.
3) Once a civilized nation was established, immigration became a legal, controlled process.
Illegal aliens are not legal immigrants - period, end of debate.
My ancestors came here legally, endured poverty, and worked honestly for generations to acrue a modest living. They were productive citizens who did not bring a drugging and raping lifestyle with them, and who did not live off governmental welfare.
In other words, white privileged genocidal oppressors.
/sarc