Researchers studying about ancient groups would look at their culture, traditional economy and irrigation methods used by the farmers.
Answer:
The practice of human sacrifice
Explanation:
"Aztec, self-name Culhua-Mexica, Nahuatl-speaking people who in the 15th and early 16th centuries ruled a large empire in what is now central and southern Mexico. ... The Aztecs referred to themselves as Culhua-Mexica, to link themselves with Colhuacán, the center of the most civilized people of the Valley of Mexico."
( my evidence to prove that)
