Well, look what site is featured on the cover of the newly released book, Aztec City-State Capitals! This book cover proves that Calixtlahuaca was indeed an Aztec city.
To get serious now, the answer to the above question depends, of course, on one’s definition of the term Aztec. Although there are a few limited uses of “Azteca” in native sources, the term is basically a modern label, so scholars have been free to use it as they please. Some writers use “Aztec” to refer to just the Mexica peoples who inhabited the imperial capital,
Furthermore, this category of people—including mostly Nahuatl speakers but also significant numbers of speakers of Otomi and other Oto-Pamean languages—has a certain unity in terms of material culture. Each region (such as the area around Calixtlahuaca) had its own ceramic types and styles, but the Aztecs as defined above shared a number of ceramic traits. Also, a basic Aztec style of architecture was found throughout this area. And that is the subject of my new book (which, by the way, I have yet to see, even though my wife informs me that ten copies from the publisher showed up in
Calixtlahuaca was a provincial city, hardly given a second thought by most of the Aztecs who lived in the
So my answer to the above question is yes, Calixtlahuaca was an Aztec city. But if someone wants to claim that it was a Matlatzinca city, that is also correct. The city was called Matlatzinco and it was the capital of a large territorial state also known as Matlatzinco, and some of its inhabitants probably spoke the language known today as Matlatzinca.
You can buy the book at the University Press of Florida.