Why did the Aztecs develop two different calendars?

The Aztecs developed two different calendars to serve distinct purposes: the sacred calendar, known as the Tonalpohualli, and the solar calendar, called the Xiuhpohualli. The Tonalpohualli, consisting of 260 days, was primarily used for religious and ceremonial events, while the Xiuhpohualli, with 365 days, tracked the agricultural year and seasonal cycles. Together, these calendars helped the Aztecs organize their society, align agricultural activities with seasonal changes, and maintain their religious observances. This dual system reflected their complex understanding of time and the interplay between the spiritual and natural worlds.