Which American civilization is the source of the belief that the world would end or drastically change on December 21st, 2012?

The Mayans are the American civilization associated with the belief that the world would end or drastically change on December 21st, 2012. This belief stems from the Mayan Long Count calendar, which marked this date as the end of a 5,126-year cycle known as the Mesoamerican Long Count calendar. While Mayan scholars and experts interpret this event as a significant shift in their cosmology rather than an apocalypse, the idea of a looming cataclysm on this specific date gained popularity in modern times, capturing widespread attention and interest.