It says, "Wait for the Europeans to tame the northland then INVADE."
Actually, most Mexicans consider themselves descendants of the Aztecs (or Mexica, hence Mexico). The Aztecs were a recent arrival to jungle America and were from what today is the American desert region. Goes to show migration and displacement of peoples is not something only European-descendees can do and is not new.
The block was carved from precious serpentine rock, suggesting it was probably a holy object used by high orders of society for some kind of ritual activity, she said. The inscription is indecipherable but scientists hope that further excavations at the site could give clues to its content.
Probably says the south western part of the U.S. is their Gods gift to them. We all have to move.