The Maya calendar is a system of calendars used in pre-Columbian Mesoamerica, and in many modern communities in highland Guatemala and in Veracruz, Oaxaca and Chiapas, Mexico. The essentials of the Maya calendar are based upon a system which had been in common use throughout the region, dating back to at least the 5th century BCE. It shares many aspects with calendars employed by other earlier Mesoamerican civilizations, such as the Zapotec and Olmec, and contemporary or later ones such as the Mixtec and Aztec calendars. Although the Mesoamerican calendar did not originate with the Maya, their subsequent extensions and refinements of it were the most sophisticated. Along with those of the Aztecs, the Maya calendars are the best-documented and most completely understood. via Wikipedia
Not only because the idea of the world coming to an end in december 2012 because a Mayan cycle was finished, it is nearly impossible to not mention the Mayan calendar while researching calendars and time. Interestingly, the Mayan calendar has managed to still be present next to the western and chinese calendar system. It shows how different societies can live around their own practices and time renderings. Even with the different periods in time for the different cultures, a day still stays a day.