Why might most of the major pre-columbian mesoamerican civilizations have existed in the areas of southern mexico?

Because the south had a favorable climate for agriculture and a variety of natural resources.

Explanation:

The Mexican territory is formed mostly by 70% of mountainous regions (whose mountains do not exceed 3,000 m of altitude) and the rest by plains. The north of the country is arid and in the south there is Atlantic forest. The Aztecs controlled a large empire that included almost all of central and southern Mexico; they chose the southern region of the country because of the favorable agriculture climate, which was the main activity of the Aztec community; and because of the natural resources provided by the Atlantic rainforest.

answer; /// i do believe but not sure(nazi propaganda)//(anti-semitism); ( holocaust) plz check first; ///good luck

dude you should crop your image so only the question shows. but   can you explain it better