The document provides information about three early Mesoamerican civilizations - the Mayans, Aztecs, and Olmecs. It describes the geographic locations and periods of each civilization. For the Mayans, it summarizes their achievements in mathematics, astronomy, architecture, and their use of hieroglyphic writing. It also outlines some of the key social hierarchies and religious practices of the Mayans, Aztecs, and Olmecs. The document thus provides a high-level overview of the origins and some defining cultural aspects of these three influential pre-Columbian civilizations in Central America.