Among other calendars devised in pre-Hispanic Mesoamerica, two of the most widely used were the 365-day solar calendar (Haab' in Mayan) and the 260-day ceremonial calendar, which had 20 periods of 13 days. This 260-day calendar was known as the Tzolk'in to the Maya and tonalpohualli to the Aztecs. Because the two calendars were based on 365 days and 260 days respectively, the whole cycle would repeat itself every 52 Haab' years exactly. This period was known as a Calendar Round. To measure dates over periods longer than 52 years, the Mesoamericans devised the Long Count calendar.