What about that other holiday, How did a land also occupied by Native Americans somehow become the most Caucasian country I've ever been in? Oh well, I'm sure they were paid fairly for their land and voluntarily decided to leave Day.... is that the same month? I keep losing track.
From Wiki:
The area now known as Argentina was relatively sparsely populated until the period of European colonization. The Diaguita of southeastern Argentina lived on the edges of the expanding Inca Empire; the Guaraní lived farther east.