https://en.wikipedia.org/wiki/Aztec_codex
https://www.britannica.com/topic/Aztec/Establishment-of-the-Aztec-empire
I have always felt that the alleged sophistication of pre-Columbian society, and the alleged post-Columbian death toll from European diseases, have been greatly exaggerated, for the purpose of political correctness.
It is very hard to believe that a functional city of 140,000 people, mentioned in the link, could exist in 1500, without wheeled carts and a written language.
I am also very skeptical that 80%-95% of indigenous Americans died from European diseases. There would have to be many well preserved mass graves that contained dozens, or even hundreds, of un-injured bodies, from all age groups.
If such mass graves exist, I have not read about them.