Here's a breakdown:
* Christopher Columbus, in his voyages in the late 15th century, was the first European to establish contact with the Americas. While he didn't establish a permanent Spanish presence, his voyages set the stage for subsequent Spanish exploration and colonization.
* Hernán Cortés, in the early 16th century, conquered the Aztec Empire in present-day Mexico. This marked the beginning of a period of extensive Spanish colonization in the region.
* Francisco Pizarro similarly conquered the Inca Empire in Peru, solidifying Spain's dominance over much of South America.
Through colonization, Spanish became the language of administration, education, and commerce in these newly established colonies. This led to the widespread adoption of Spanish by indigenous populations and the eventual emergence of a diverse range of Spanish dialects in the Americas.