The most annoying thing about the “Mayan Prophecy” is that it isn’t Mayan. It’s a “prophecy” made by moderns about the Mayans, made by people who either misunderstand or willfully misrepresent their numerical and calendrical system. Some more reasonably minded folk have suggested the Dec 21st, 2012 date is nothing more than a Mayan equivalent to our own modern Y2K bug of a decade ago, but in reality it’s not even that. The Mayan long count calendar is perfectly capable as it stands of representing another 2,365 and a half years before it runs out of digits and has to reset the way our digital calendars rolled over from 99 to 00 without a column to indicate the century.
To understand what the date does represent, it’s first necessary to gain a very basic understanding of how the long count calendar (used by much of Mesoamerica and not just the Maya) notates dates. First, the Mayan numbers were written in a base-20 not in the base-10 number system we know in most of the western world today). That is, whereas with our numbers each column of digits indicates a number from 0 to 9 before rolling over into the next column to its left, a Mayan number has symbols from 0 to 19. A further complexity is that in their calendrical system, the second column from the bottom (their dates are written vertically) only goes from 0 to 17, then the remaining three columns return to the 0 to 19 count (this allowed a full run of the second and first row to indicate 360 days, the equivalent to their year). In most modern transcriptions of the dates, we use a simple notation of 0.0.0.0.0 where the leftmost position correlates to the one traditionally on top and the right to the bottom. So we have a possible range of 0 days (0.0.0.0.0) to 2,879,999 days, or about 7,885 years (188.8.131.52.19).
All December 21, 2012 corresponds to is the date 184.108.40.206.0, a period of 1,872,000 days, 5,125 years, since what the Maya held to be the date of “creation” of the current cycle in 3114 BCE, which is simply the last time they indicated the date to be 220.127.116.11.0 (which leads to one of the speculations that the topmost rung of the calendar may only go from 0 to 13 in the same way that the second rung only goes from 0 to 17 rather than the full 0 to 19).
This whole “prophecy” mess got started with the discovery of what’s now known as the Bernal tablet during some roadwork back in the 1960s. It’s a large Mayan stele which originally held a great deal of text, including a passage identifying 18.104.22.168.0, the Dec 21st, 2012 date. However, the tablet is badly damaged with missing portions and more than a few passages on the surviving parts eroded or otherwise illegible including the part about just what it is that’s supposed to take place on that date. There remain only some vague remarks about the little known Mayan god “Bolon Yokte”, apparently associated in some way with “creation”, however just what his association is with the date is obliterated from the tablet. While you can find many of the 2012-world-ending sort today claiming it says Bolon Yokte will “descend from the sky” or whatever (which is anyone’s guess as to what that supposedly means), the archaeologist Bernal, who did the original translation, made it explicitly clear that the passage was speculation on his part and not at all visible on the tablet. It is just as reasonable, perhaps more so, to assume a reference to a god of creation is only in observation of the calendrical date being the same as that assigned to the original “creation” myth.
Given that other Mayan inscriptions list dates far in the future of 2012, it’s very obvious that they themselves didn’t believe 2012 would be an apocalyptic end of the world. For instance, an inscription to commemorate the (future) anniversary of the 80th calendar round of K’inich Janaab’ Pakal’s coming to the throne projects to a date of October 21st, 4772 c.e. And despite the typical representation of long count dates as having only five parts, as detailed above, there are texts that add several more. The stele known as Quiringua F shows 22.214.171.124.0.1 and subtracts a “distance date” of 126.96.36.199.188.8.131.52.0 producing a final date over 90 million years in the past. On stele D from the same site, there’s a date of 184.108.40.206.0.7 that adds a distance date of 220.127.116.11.18.104.22.168.0 which would be more than 400 million years in the future from the time the stele was erected (circa February, 766 c.e.). Rather dwarfs 2012, doesn’t it?
As for the association of the Mayan god to the date, if one considers comparative religion in general and not just a Mayan focus, the association of deities or supernatural entities generally, to calendrical cycles isn’t at all unusual or even overly significant. The Hindu system of yugas is particularly similar, citing the world to currently be in the Kali yuga (कलियुग), which they say began 3102 b.c.—only 12 years after the beginning of the current Mayan cycle. Curiously, they indicate the Kali yuga as the 4th cycle, while the Mayan text, the Popol Vuh, claims the current cycle is also the 4th. But don’t read too much into it: these kinds of coincidences happen all the time if you read broadly enough in comparative studies.
In the end, the point is simply this: there is no prophecy by the Mayans that the world or anything else—other than a calendrical cycle!—ends in 2012.