There have been migrations of people north and south of what is now the US-Mexican border for thousands of years. Long, long before there was an “Aztec” political entity at Tenochtitlan, which was quite recent, only 150-200 years prior to the Spanish conquest.
And there was a Nahuatl (the language of the Aztecs)-speaking cultural continuum all over central Mexico for maybe a thousand years (probably more) before Tenochtitlan. The Toltecs spoke Nahuatl.
And there was human sacrifice and cannibalism as well, likely for thousands of years, both north and south of the current border. Ref. “Man Corn”, C.Turner - scary stuff.
Human sacrifice was part of the dominant culture.
Not the best culture to raise your children