What might have been one of the biggest geographic influences on mesoamerican civilizations?

One of the biggest geographic influences on Mesoamerican civilizations might have been the highlands. The high peaks that surround the valleys where indigenous cultures developed, made rain a rare event, so they had to think about a way of storing water. By struggling to make the most of essential natural resources, the identity of such groups was forged and it allowed it to grow and to strengthen as a civilization.