That must be why they mostly have names like Rodrigues, Cardones, Gonzales, and so forth. The Spanish conquered what is now Mexico first, although not by all that much. The old Spanish Colonial cities of St. Petersburg (FL, USA), San Juan (Puerto Rico, USA), Campeche (Campeche MX), and Barranquilla (Columbia) have much in common. They are/were all walled cities. The walls designed to keep out the pirates (who were often English). Campeche calls their baseball team "The Pirates" (Los Piratas).
The Mexicans are not related to South American peoples, except in so far as they share Spanish ancestry, and Amerind ancestry, although the Amerind ancestors represents a large diversity of cultures. (Aztec, Maya, Inca, and many others)