Listed below are the Calendars of Azeroth, each itself a timeline of events specific to its niche in the world of Azeroth.
Lotharian Calendar (LC. and PC.)Edit
The Lotharian Calendar was adopted after the coronation of Varian Wrynn, and, due to Stormwind's prominence among the nations of the Grand Alliance, would become the basic calendar for many of those under it. Its Year Zero is the opening of the Dark Portal and the start of the First War. It is named in honour of Anduin Lothar.
For ease of use, and to avoid writing dates in negative, the custom eventually came about of writing dates before 0 LC as being 'PC', or 'Pre-Calendar' (the commonly supposed 'Pre-Calamity' is a neologism). Thus, the Dark Portal reopened in January 26 LC, the Invasion of Northrend began in the winter of 27 LC, while the independence of Stormwind was in 592 PC. The present year is 31 LC.
The King's Calendar (K.C. and P.C.)Edit
Before the First War, Stormwind humans counted forward from the end of a long and bloody civil war which occupied the latter half of the 6th century PC. The war ended in 592 PC with the founding of the Kingdom of Stormwind. The calendar begins counting at this date, although it was adopted somewhat later, and continued to be used officially until the fall of Stormwind. Even afterwards, however, many government documents dated by the king's calendar, as do numerous pamphlets, publications and personal writings that we have. (The Timeline on this Wiki follows this calendar.)
Thoradine Calendar (A.D)Edit
Counting from the unification of Arathor under its first King, Thoradin, the Thoradine Calendar begins in 2,770 PC and, though falling out of favour with some of the newly-founded Seven Kingdoms, was used by the Church from its foundation. It eventually came to be standard throughout the Seven Kingdoms until the fall of Lordaeron.
A.D. stands for A'no Dominaeum, or 'In The Year of [Arathi] Rule'. Note that this comes from the Church, which used Humanised Thalassian for all official writings; the original nomenclature would have been in Old Arathi.
Gnomish Calendar (G.C.)Edit
The Gnomish Calendar counts from the overthrow of the Last King of Gnomeregan and the foundation of the Gnomish Republic. It was adopted unanimously by the new government in 367 PC, and, though its use diminished with the Fall of Gnomeregan, many gnomes continued to employ it between their fellows. Dates before the beginning of the calendar are signified by writing the numbers backwards.
Kaldorei Calendar (P.S.)Edit
Night Elves adopted their calendar roughly 10,000 years ago, shortly after the Great Sundering, as they began to recover from the explosion. Although some have adapted to the Lotharian Calendar after living in the Alliance lands for some time, this one is still almost universally used by all night elves in northern Kalimdor. Any dates Before Sundering, although rare, are marked as 'B.S.', and the vast majority of dates are marked 'P.S.', or "Post Sundering".
Adapted from the Earthen Ring Wiki before its deletion.