The Mayans were able to track the position of the planets and sun in our solar system, not only in relation to each other, but also in relation to the galactic equator over a 3600 year cycle, accurate to within seconds.
Carefully consider this;
Ancient cultures were dependent upon successful agriculture, which required they pay attention to time as it related to the seasons, which is dependent upon the circumstances and conditions of the Earth's behavior in space. It is entirely perceivable how an ancient culture would have noticed a few patterns over time.
They knew that when this or that gets to that position in the sky, warmth and rain was to follow, that it was time to plant in preparation for food stocks next winter. Their survival depended on it, so they were paying attention.
They were able to track the position of the solar system relative to the galactic equator over a 3600 year cycle. How and what would that kind of knowledge require?
In order to recognize it as a cycle or pattern, it would have had to have been monitored for several cycles. After that, it would have to be tracked and logged through each cycle, evolving and refining each time to eventually produce knowledge of the galactic equator as it relates to the rest of the galaxy and universe.
That would take a LONG time to develop such knowledge, perhaps hundreds of thousands of years of a civilization studying the sky. This suggests that the Mayan culture goes back much further, or they were much more advanced, than we currently understand.
It could suggest that they were given knowledge to develop from, a boost of sorts, by someone who already knew about said cycle.