* Origins of Nahuatl: Nahuatl is a Uto-Aztecan language, meaning its roots lie in a group of languages spoken by people who migrated into Mesoamerica from the north.
* The Aztecs' Ancestry: The Aztecs (more properly called the Mexica) were one of many groups who spoke Nahuatl, and they were part of the Nahua people.
* Spread and Influence: As the Aztecs rose to power, their language became dominant across a vast region, spreading through conquest and trade. Nahuatl became the language of administration, law, religion, and even daily life for many people in the Aztec Empire.
So, it wasn't a conscious decision: It was a matter of their cultural heritage and their historical circumstances that led to the Aztecs speaking Nahuatl.