Indigenous Maya people in southern Mexico Wednesday began a year-long countdown to Dec. 21 2012, which some believe will bring the end of the world.

Known as the "2012 Phenomenon", December 2012 is prophesised to mark the end of a five-millennia cycle in the ancient Mayan calendar.

The prophecy also predicts that a cataclysmic or transformative event will take place on Dec. 21, 2012, which some believe to be predicting the end of the world.

The winter solstice in 2012 marks the end of the 13th Baktun, a date of special significance that reflects celestial alignments recognised by modern astronomers.

The idea that it could mean the apocalypse - based on a Mayan text carved into a stone 1,300 years ago - has been spread on thousands of websites.

But experts and astronomers have contested this belief, saying it signifies the end of an era and not the end of the world.

They point out that other Maya prophecies refer to events far in the future, but this has not stopped the spread of apocalyptic beliefs.

Mayan priests and communities have begun preparations for the historical date, and Mexican tourist officials are preparing for a surge in visitors to the region.

Mexico's tourism agency says it hopes to draw around 52 million visitors in 2012, reports the BBC. The majority will be heading to the southern Maya heartlands of Chiapas, Yucatan, Quintana Roo and Tabasco.

The Mayan civilisation reached its peak between 250 and 900AD and was deeply fascinated by astronomy, mathematics and time cycles.

According to Mayan codes researcher Sven Gronemeyer, the 2012 date was "a reflection of the day of creation" and also signified the return of Bolon Yokte, the Mayan god of creation and war.

"There is no prophecy for 2012. It is a marketing fallacy," said Erik Velasquez, etchings specialist at the National Autonomous University of Mexico.