What were the key cultural and scientific accomplishments of early mesoamerican cultural groups?

The ancient Maya, a diverse group of indigenous people who lived in parts of present-day Mexico, Belize, Guatemala, El Salvador and Honduras, had one of the most sophisticated and complex civilizations in the Western Hemisphere. Between about 300 and 900 A. D., the Maya were responsible for a number of remarkable scientific achievements-in astronomy, agriculture, engineering and communications.