The Aztec Empire fell in 1521, but of course its people didn't disappear. If the codices date after 1603, that's plenty of time for the Spanish to influence the

The Aztec Empire fell in 1521, but of course its people didn't disappear. If the codices date after 1603, that's plenty of time for the Spanish to influence their lives, even without full absorption. That San Andrés Tetepilco has a partly-Spanish name now doesn't necessarily imply that Spaniards had a role in its founding or lived there in significant numbers at the time the codices were written. The church might have been founded by a Spanish missionary, but it might also have been an Aztec convert instead. The history apparently also covers events that happened under Spanish rule, so it's not entirely about a non-Spanish topic either.