They had a month of 20 days, 18 months each year (360 days) and after that continuing to groups of 20 they could go up to 'alautun' that was 23.040.000.000 days! (It is correct, billions!). On labels found at the place Kiriga there are reported facts before 90.000.000 years, and other labels writes about 400.000.000 before!
For small time periods Mayas were using the 1/20 of the day (our 1 hour and 20 minutes), and their minute was the 1/20 of their hour (our 4 minutes). They had calculated the true solar year to 265.242 days, the lunar year and the year of Venus at 224.7 days. But with this calendar they were using also another one with 13 months of 20 days, that none knows to what is connected... Some unknown planet? They also knew the existence of planets Uranus and Neptune. We learned their existence at 1781 and 1846...
And pretending that we don't see all the above the 'official history' insists on beliefs that Mayas had a very simple agricultural structured economy! Their huge libraries burned from the Spanish soldiers that gave this way the lights of European civilization to these 'barbarians'... We lost a lot of valuable information from these libraries. After that Mayas without a fight, they disappear in the jungle for more than 300 years.
A civilization with almost 120 cities in the heart of tropical jungle of Yucatan, with no roads to connect them, without weapons for defence, that were using the wheel only for kids toys, manage to made impressively buildings with rocks transferred from Guatemala. They probably were using a different but effective way for transportations and communications. But who knows what?