Among other calendars devised in pre-Columbian Mesoamerica, two of the most widely used were the 365-day solar calendar (the Maya version is known as the Haab’) and the 260-day calendar, with 20 periods of 13 days. In Mayan studies this 260-day calendar is known as the Tzolk’in; the equivalent Aztec calendar is known in Nahuatl as tonalpohualli.
The Haab’ and the Tzolk’in calendars identified and named the days, but not the years. The combination of a Haab’ date and a Tzolk’in date identifies a specific date in a combination which did not occur again for 52 years. The two calendars based on 365 days and 260 days repeat every 52 Haab’ years, a period generally known as the Calendar Round. To designate dates over periods longer than 52 years, some Mesoamericans utilized the Long Count calendar.