Carbonell Abenmenax is credited with creating the calendar, and it is sometimes called the Abenite calendar, or simply the Terrasan calendar. It divides known history into three distinct ages, while admitting that an earlier age (or ages) must have existed, it is impossible to know any dates from them with any kind of certainty at all. The first age is the Age of Legends (A.L.) Many events during the age of legends are legendary or semi-legendary, hence the name, and dating for many events is imprecise or unsure. The Age of Legends lasted for 1972 years, from the traditional date that people arrived on the shores of the Mezzovian Sea (although there are lots of good reasons to believe that date is much older than what tradition dictates) to the rise of the Balshatoi kingdoms. The following Age of the North (A.N.) refers to the hegemony that people of Balshatoi, or proto-Balshatoi ethnicity dominated the region in a succession of nations and cultures and subcultures. The Age of the North lasted 843 years. It ended when Queen Gualharda d'Coysset officially declared the independence of Terrasa from foreign domination after many years of low-grade civil war, and this time was able to make it last. From that point on, no northern power has officially controlled any land on the southern coastline.
The Age of the South (A.S.) is the current age, referring to the gradual domination culturally and politically of ethnic Terrasans and their close relatives of the Mezzovian area (although in both Kurushat and Baal Hamazi, it is believed that year 1 A.S. is also the year that their own kingdoms were founded. And the arrival of the jann in Qizmir is not precisely dated; scholars there are starting to publish as fact the idea that they arrived from far to the east in 1 A.S. too, making the current age the semi-mythical founding date of all four of those major powers.) From the humble declaration of independence of Queen d'Coysset to the rise of what has come to be called the Terrasan Empire was a long journey, and for much of the first two centuries of the of the Age of the South, it was arguably a misnomer. And pundits, philosophers, politicians, and others who wish to make a point for whatever reason question whether maybe a new age shouldn't start now, as the old Terrasan power fades. Indeed, in Porto Liure, some scholars believe that the independence of that city-state will be seen in retrospect as the beginning of a new age where local politics and forces dominate, and no regional superpower controls the entire Mezzovian Main. Some of them have even started unofficially referring to the current age as the Age of Freedom, but that terminology has not caught on broadly, and mostly those scholars are mocked for their presumptiousness. Today's date (well, that can move around from time to time, so it's give or take 5-10 years or so, of course) is 567 A.S.
Abenmenax also created the divisions within each year that are widely used throughout the region. The 365 day year was divided into twelve 30-day divisions, with a 5 day holiday at the end of the year to make up for the remaining days. For reasons that are lost to the mists of time, Abenmenax decided to have the year officially end at the summer solstice (keep in mind that the Mezzovian Sea and all of the lands described here are in the southern hemisphere), so the year officially starts five days later. The month names in standard Terrasan are as follows: Gener, Febrer, Março, Abril, Majiol, Jugniol, Juliol, Agost, Setembre, Octubre, Novembre and Desembre. And last five days of the year do vary by region; each region naming them after local heroes or gods or rulers. In the Terrasan city-states, they are known, in order as el día Cherno (or simply Cherno), Peruno, Velo, Selvano, and el día Culsano.