Their differences in religion made Maya, Aztec, and Inca have different calendars. The Mayans made a calendar with their knowledge of astronomy. The priest’s duty was to advise the correct days to plant, wage war or anything. The Mayan calendar was very advanced, it had a year of three hundred sixty five days. For the Incas we think their calendar based on the observations of the sun and moon to the stars. We have very little evidence on the Incas having a official calendar. The Aztec calendar is the calendar system that was used by the Aztecs and shared with the other people of central Mexico. These calendars for all three religions were an important part of their