Trump should know that real natives in the US did NOT have orange skin and yellow hair.
I love watching those Youtube videos where drunk European women are telling Asian women to go back where they came from.   You cannot explain to these idiots that they are as much an immigrant as the person they are attacking.  But Mexicans are not native to North America either - they also came from Europe.
Mexicans ... well in the end we all come from some mokey out there in Africa or from some migration thereof, but many many Mexicans are actually natives - genetically - from Mayans, Aztecs and the like in maybe 80%. The Spanish conquer caused certainly plenty of pain in Latin America, but the locals were NOT systematically anihilated - more of the contrary - got mixed.
On if this was long ago or not, that is not the point, the point is that nearly everyone is an inmigrant. Xenophobia is senseless in this context. There is not "cultural assimilation" or other undesirable effects.