Scientists have re-checked the system of long-count with a modern European calendar. This is necessary for accurate dating of historical records.
This is not a picnic. Maya pooled days (kin) in 20-day cycles (uinaly), which in turn accounted for tun (one tuna – uinalov 18 and 360 days). 20 tuns – it Katun (about 20 years), and 20 katuns – Baktun duration of 144 thousand days, that is a little less than 400 years. Closing one of the baktun just has fueled speculation about the end of the earth