I'm reading my US History textbook, and it states:
"In 1519, the governor of Cuba authorized Cortes to organize an expedition of about six hundred men and eleven ships to investigate rumors of a fabulously wealthy kingdom somewhere in the interior of the mainland."
This is implying that people have been there or have met people that have. Did this happen?
Cortes was the first. The source of the rumors was likely earlier encounters between Spanish explorers and natives from the coast of Mexico. Since the Aztec empire was so incredibly vast, peoples for hundreds of miles would have been aware of them (and would most likely be paying them exorbitant tributes in return for peace), so any Spaniard/European that came into contact with a tributary society of the Aztec would have likely heard about them.