22 dic 2012 año aC - Mayan calendar
Descripción:
 The Maya calendar consists of several cycles or counts of different lengths. The 260-day count is known to scholars as the Tzolkin, or Tzolk'in. The Tzolkin was combined with a 365-day vague solar year known as the Haab' to form a synchronized cycle lasting for 52 Haab', called the Calendar Round.
Maya calendar - Wikipedia
https://en.wikipedia.org/wiki/Maya_calendar 
Añadido al timeline:
fecha:
22 dic 2012 año aC
Ahora mismo
 ~ 4041 years ago