While no exact timeline was published in Lands of Mystery, Brann Bronzebeard establishes approximate dates for several events. Based on the references the book appears to take place between 29 and 30 years after the opening of the Dark Portal.
10,000 years ago
all the lands in Azeroth were part of the same giant land mass: the primeval Kalimdor.[1]
The Eternal boar named Agamaggan fought and died in the battle against the first coming of the Burning Legion.[3]
since the destruction of Eldrath during the Sundering.[4]
At the end of the War of the Ancients, the powers released in the Well of Eternity blasted the well downward, smashing through seawater and rock, driving it into Azeroth's molten core. The core is still exposed. The Maelstrom is created.[5]
since the construction of statue of Kur'alos Ravencrest.[4]
C. 9,000 years ago
Archdruid Fandral Staghelm was born about a thousand years after the Sundering (making him over 9,000 years old).
500 years ago
Magna Aegwynn, Guardian of Tirisfal, slew the demon Sargeras.[2]
Bloodsail Buccaneers start clashing with the Blackwater Raiders.
3 years ago
Lester Zank reunites with Duke Falrevere and becomes a Bloodsail Buccaneer.[15]
2 years ago
The Lich King summoned Arthas back to Northrend.[16]
Arthas and the mighty Anub’arak traveled through Azjol-Nerub on their way to the Frozen Throne.
The human druid Mitrius starts livng on the Shiverwind Coast.[17]
Admiral Proodmoore's death. Thrall and Jaina kept a tenuous peace since that time, but hostilities between Horde and Alliance had begun to affect Theramore. Trade between Theramore and Orgrimmar had all but ceased, and vigilantes from both factions strike against merchant caravans.[18]
Timeline with an attempt to be based on all sources of information and all versions of the timeline. May not be consistent with the latest official timeline.
Timeline (from official site, 2010)
Timeline based on the official site (2007) timeline with added dates.
Timeline originally published by Blizzard in the Warcraft I manual (1994), with further dates established from the Warcraft II manual (1996), Beyond the Dark Portal manual, and Warcraft III manual. Also includes dates mentioned in the RTS games themselves.