The Aztecs had two main calendars that they used for different purposes: the Tonalpohualli and the Xiuhpohualli.
The Tonalpohualli is a 260-day ritual calendar, primarily used for religious and divinatory purposes. It consists of 20 periods of 13 days, with each day having its own significance, and it played a crucial role in ceremonies, agriculture, and personal fortune telling.
The Xiuhpohualli, on the other hand, is a 365-day solar calendar that corresponds more closely to the modern Gregorian calendar. It comprised 18 months of 20 days each, plus an extra five ‘nameless’ days added at the end of the year. This calendar was used primarily for agricultural cycles, festivals, and civic events.
Together, these two calendars formed a comprehensive system that governed the daily lives of the Aztec people, intertwining their agricultural, religious, and social activities.