I believe the Mayan's were shown how to construct their calendar in order to match events that are about to unfold, and the knowledge suggested by the design of the calendar, including astronomical coincidences that would require a high degree of sophistication to measure, was passed to them through their “feathered serpent” deity Quetzalcoatl. It is near the time of the earliest recorded appearance of this odd deity that the calendar was invented, around 355BC

See We live in a story article at UnitedStatesofGod.org for a detailed graphic showing the Mayan long count calendar's precession numerology

See the book “Mysteries of the Great Cross of Hendaye – Alchemy and the End of Time” by Jay Weidner and Vincent Bridges or check JayWeidner.com for more information