Official Timeline

If anything remotely important is missing, leave a comment below with information and perhaps even links, and I'll put it in! If anyone has any fixes or suggestions, don't hesitate to let me know. This is going off of the Official, Blizzard-approved timeline with help from the Visual Guide.
*Year -25,000 - The draenei leave their home world of Argus. 
**A good majority of the eredar of Argus follow Kil'jaeden and Archimonde, two of their leaders, into the ranks of Sargeras. The other eredar, calling themselves the draenei, accompany Velen in joining the naaru and escape on the dimensional ship Oshu'gun. 
*Year -12,000 - Downfall of the Mogu Empire. 
**Throughout many emperors' reigns, the pandaren may have attempted several failed uprisings. Finally, the pandaren form a sturdy rebellious force and overthrow the mogu, building an empire of their own. 
**After the fall of the mogu empire, the Zandalari trolls launch a full-scale invasion upon Pandaria to destroy the pandaren empire and restore the rule of the mogu. The mogu clans, no longer led by a central ruler, began to break up and fall, assisting the Zandalari in their decline. /
**Zandalari forces are defeated after the besiege on Dawn's Blossom. After the war, the mogu clans scattered completely, and most of them were not seen again for centuries. /
*Year -10,000 - War of the Ancients. 
**After recklessly pursuing the use of arcane magic and manipulating the powers of the Well of Eternity, the night elves catch the attention of Sargeras. War erupts between the night elves faction (including Eternals, dragons, and a faction of Highborne) and the demonic forces of Sargeras's Burning Legion. 
**The Well of Eternity is destroyed and the Great Sundering splits the continent of Kalimdor. The Watchers are formed to look after Illidan's prison, with Maiev Shadowsong becoming the first Warden. 
**The majority of male night elves enter the Emerald Dream. 
*Year -9,000 - The World Tree Nordrassil is made and the War of the Satyr occurs.  
**The satyrs organize to attack the night elves. While the night elves felt a heavy toll at the end of the war, any sort of central leadership in the satyrs was decimated. During this war, night elves first used the worgen form. After several night elves had been infected by the worgen curse, the Druids of the Scythe were banished to the Emerald Dream. /
*Year -7,300 - The Highborne are exiled from Kalimdor after a display of reckless power in the form of a destructive arcane storm. They brave the Maelstorm and land upon the shores of Tirisfal, renaming themselves the high elves. /
*Year -6,800 - Quel'Thalas is founded by the high elves. 
**The high elves use a vial of water from the Well of Eternity to create a new fount of power, calling it the Sunwell. 
*Year -2,800 - The Troll Wars occur and formation of the great nation of Arathor begins. //
**The high elves of Quel'Thalas fight a brutal conflict with the native Amani trolls of the region. Recognizing the benefits of joining forces, the high elves form an alliance with the organizing humans and teach the first one hundred humans magic in return for assistance with the troll threat. //
**The first collectives of high elf warriors and rangers form to combat the troll threat. 
*Year -2,700 - The first Guardian is appointed. 
*Year -2,500 - Ironforge is founded. 
*Year -1,200 - The seven kingdoms of humanity (Arathor/Stromgarde, Alterac, Azeroth/Stormwind, Dalaran, Gilneas, Kul Tiras, and Lordaeron) are founded. 
*Year -930 - The draenei ship lands upon Draenor. /
**The spirits of the orc ancestors begin communing with the naaru K'ure, and the orcs themselves revere the giant spacecraft, which they name Oshu'gun, or "Mountain of Spirits", as a holy place. 
**Shattrath is built in Terokkar Forest as the capital city for the draenei, while The Temple of Karabor is built in Shadowmoon Valley as a sanctuary for the prophet Velen. 
**Orcs and draenei enter into a cordial, trade-based relationship. Draenei embrace hunting for the first time as a means of gathering food. The races are distant, but in good relations. /
*Year -925 - War of the Shifting Sands. /
**The inhabitants of Kalimdor fight back against the dangerous Silithid and Qiraji of Silithus. The battle ends with the creation of the Scarab Wall and retreat of the monsters. They were trapped behind the wall for many, many years. /
**Southwind Village in Sithilis is horrifically destroyed in the aftermath of the war. 
*Year -823 - Aegwynn clashes with Sargeras's avatar. 
*Year -500 - Official formation of the Farstriders. 
**Before this point they had no real organization beyond that a few hunters would gather together temporarily in order to fight off threats to Quel'Thalas. They are the second official organization, coming after the Magisters but before the Blood Knights. 
*Year -230 - The War of Three Hammers. 
**The Dark Iron clan, Wildhammer clan, and Bronzebeard clan go to war with each other after High King Anvilmar's death for control of Ironforge. This war raged on for years before ending with the Bronzebeard clan as victors. The Bronzebeards and Wildhammers soon afterwards band together to fight off the Dark Iron forces. 
**As an end result of the war, Grim Batol is left uninhabitable. The Wildhammer dwarves later build Aerie Peak in the Hinterlands as the Bronzebeards claim Ironforge. 
*Year -200 - First recorded contact between dwarves and gnomes. /
**Gnomes are found by their dwarven cousins and Gnomeregan is built in the mountains of Khaz Modan. Previously, the gnomes were considered mythological creatures. /
**Dwarves discover and utilize gun powder for the first time. 
*Year -10 - Stormwind Assassins (later called SI:7) is formed. 
*Year -5 - Rise of the Horde. 
**Blackhand is made Warchief. 
**The Shadow Council is formed, causing the first orcs to gain green skin due to the fel taint. 
**The draenei slaughter begins, ending with a total of roughly eighty percent of the race annihilated. /
**The Temple of Karabor is conquered and becomes the Black Temple, a headquarters for the Shadow Council. /
*Year -1 - Orc chieftains drink demon blood. Sacking of Shattrath. /
**Draenei flee to Zangarmarsh, with many remaining behind to either defend Shattrath or in a worst-case scenario die in order give the orcs the illusion of a total victory to cover the escape. Families, including children, were among those that stayed behind and gave up their lives. /
**Many of the draenei that somehow survived the sack of Shattrath were exposed to high amounts of fel energy, causing them to mutate into what would become known as the Krokul, or Broken. A handful of others become the Lost. 
**Nobundo loses his connection to the Light. Within a year or two, he becomes the first draenei shaman. 
*Year 0 - Dark Portal is made, and so begins the First War. /
**The very first orcs set foot in Azeroth and, in a blood rage, begin to wage war with the humans for their land. This war ends with them being victorious and gaining the south of the Eastern Kingdoms for themselves. /
**The Brotherhood of the Horse, also known as the Knights of Azeroth, are largely decimated in the invasion. 
**Goblins begin building their trade empire. 
**The Frostwolf Clan flees through the Dark Portal and settle in the Alterac Mountains. 
**For the most part, high elves remained involved during the First War. Some may have participated for various reasons, but only by rare exception. 
**At the end of the war, Orgrim Doomhammer challenges and kills Blackhand for the title of Warchief, subsequently slaughtering the Shadow Council. 
*Year 3 - Knights of the Silver Hand founded in Stratholme. /
**Uther the Lightbringer becomes the first human paladin. 
*Year 5 - The Fall of Stormwind. 
**Moonbrook, Goldshire, Stormwind, and Northshire all fall to the Horde. The Redridge Mountains fall largely to the Blackrock orcs. /
**King Liane Wrynn is assassinated and the survivors from the razing of Stormwind City flee to the north to the Kingdoms of Lordaeron. 
**Anduin Lothar tells King Terenas Menethil II of Stormwind's fall and the impending orcish assault. Terenas unites the seven human kingdoms, and later the dwarves, the gnomes, and the high elves, forming the Alliance of Lordaeron to combat the Horde. ////
*Year 6 - The Second War. Internment camps are made. /
**After brutal and bloody fighting, the Alliance of Lordaeron triumphs over the Horde at Blackrock Spire. Anduin Lothar is slain by orc Warchief Orgrim Doomhammer. General Turalyon leads the forces of the Alliance after Lothar's death, and crushes the remnants of the Horde armies. The remaining orcs (all but the Frostwolf and Warsong clan) are rounded up and placed in internment camps, and the Dark Portal is destroyed. /
**Stratholme is destroyed during the war, but is rebuilt shortly afterwards. Moonbrook, Goldshire, Stormwind, and Northshire begin rebuilding after the war. Greymane Wall is built, separating Gilneas from the rest of the world, and Kul Tiras officially leaves the Alliance. /
**The technology feud between gnomes and goblins begins, as gnomes provide tech for the Alliance and goblins for the Horde. /
*Year 8 - The Invasion and shattering of Draenor. ////
**The orc shaman Ner'zhul utilizes the rift that remains after the Dark Portal's destruction to send orcs into Azeroth once again. Alliance forces, known as the Alliance Expedition, are subsequently sent through the rift to Draenor, where they continue to fight the remaining Horde forces and are abruptly stranded. /
**The world of Draenor is strained by the vast energies that result from Ner'zhul's numerous portals, and as a result, Draenor is shattered; a large fragment becomes the realm of Outland. /
*Year 10 - Alexstrasza is freed from the Dragonmaw clan. 
*Year 14 - The completion of Stormwind. 
**After the completion of Stormwind, the unpaid Stonemason's Guild is kicked out of the city after inadvertently killing queen Tiffin Wrynn, shortly thereafter forming the Defias Brotherhood under Edwin Van Cleef. Taking over Moonbrook, the People's Militia is formed to combat the threat. 
*Year 18 - The orcs are freed from the internment camps and form the new Horde. 
**The orcs held in the Alliance's internment camps are freed by Orgrim Doomhammer, Grom Hellscream, and Thrall, an orc who was raised by humans as a slave and gladiator. Thrall is named Warchief of the new Horde. 
**Alterac is left in ruins after unresolved disputes over leadership. The remaining nobles resort to thievery and form the Syndicate, later basing themselves in Durnholde Keep after the liberation of the internment camps. 
*Year 19 - Thrall and Tirion Fordring rescue Eitrigg from execution. /
*Year 20 - Also known as the Reign of Chaos. The Third War begins. /////
**The Burning Legion launches another assault on Azeroth using the Lich King. The Plague of Undeath spreads throughout the kingdom of Lordaeron, resulting in the rise of the Scourge in Lordaeron. Arthas purges almost all of its inhabitants of Stratholme. The Scourge eventually take control of the city. Andorhal also falls during this time. /
**The Forsaken first make their appearance, currently mindless and entirely under the Scrouge control, victims of the Plague of Undeath. 
**Prince Arthas Menethil falls to corruption, taking up the cursed runeblade Frostmourne and murdering his father King Terenas Menethil II. 
**The Sunwell is defiled, and the demon lord Archimonde is summoned into Azeroth. Tranquillien, Silvermoon City, and all of Quel'Thalas along what is now the Dead Scar fall as the Sunwell is corrupted and destroyed by Arthas, slaughtering ninety percent of the high elf population. Kael'thas returns. King Anasterian Sunstrider was killed by Arthas and his son, Prince Kael'thas Sunstrider takes over the throne. Sylvanas Windrunner was also killed during this time, slain by Arthas and turned into a banshee. The high elves begin experiencing magic withdrawal. 
**A squad of elves return with Kael'thas returns from the Outlands. They teach the remaining elves how to absorb fel and, in doing so, caused them to gain fel green eyes and turn them into what is now known as blood elves. The blood elves officially split from the Alliance and Lady Liadrin becomes the first Blood Knight. 
**Dalaran is destroyed by Archimonde. In the aftermath of the war, the city starts to be rebuilt, and eventually moved to its current position above Crystalsong Forest in Northrend. 
**Stromgarde is invaded by the Syndicate, Boulderfist ogres, and Witherbark trolls. 
**Gnomeregan is invaded by troggs, which combined with the ill-advised venting of radioactive waste tanks wipes out eighty percent of the gnomish population and keeps the gnomes significantly absent from the Third War. The survivors resettle at Ironforge in Tinkertown. 
**Many survivors flee to Kalimdor, including humans led by Lady Jaina Proudmoore, and orcs led by Thrall, both directed by the Prophet Medivh. In Thrall's travels across the seas, he encounters the Darkspear trolls, rescuing them from both the Kul Tiras navy as well as the combined forces of the murlocs and naga. Upon landing in Kalimdor, the trolls settle in the Echo Isles. //
**Thrall's Horde stumbles upon the tauren and assists them in taking back Mulgore from the taurens' age-old enemies, the centaurs. The tauren agree to join forces with the Horde, putting aside their previously nomadic ways. /
**The night elves are found by the orcs as they attempt to cut down their forests in the Northern Barrens and Southern Ashenvale. The orcs fight fiercely against the night elves and end up killing one of their leaders, Cenarius, in their blood fueled campaign. The majority of the males exit the Emerald Dream. /
*Year 21 - The Battle of Mount Hyjal. //////
**At the Battle of Mount Hyjal, Archimonde is defeated and the World Tree is destroyed/damaged, resulting in the loss of the night elves' immortality. The night elves maintain their relationship with the Alliance after the end of the war. Even the Horde assists with the death of Archimonde. //////
**A new attempt at a World Tree, Teldrassil, is created by Fandral Staghelm. Although it did not have the power to regain their immortality, the night elves use it to house their new capital, Darnassus. 
**The night elves commemorate their first female druid and male priest with a pair of statues. 
*Year 22 - Rise of the Lich King.
**Arthas Menethil travels to Northrend. He ascends Icecrown Glacier, shattering the Frozen Throne and taking his place as the Lich King.
**With the Lich King weakening and Sylvanas betraying Arthas, a large group of the Scourge break free of the Lich King's will on them and join under the banner of the Forsaken. With hate brewing inside of them, the Forsaken promise to destroy the Scourge for what they have done to them. They claim the ruins of Lordaeron as their home. 
**In the aftermath of the death of Uther the Lightbringer, the Scarlet Crusade is formed. 
**The cities of Orgrimmar and Thunder Bluff are founded in Kalimdor. The Shattered Hand Clan in Orgrimmar become the new Horde's guild of rogues and assassins. /
**Zalazane overtakes the Echo Isles, forcing the rest of the Darkspear to settle in Sen'jin Village on the coast of Durotar. 
**The human city of Theramore is founded by Jaina Proudmoore in Eastern Kalimdor. Meanwhile, in the Eastern Kingdoms, rhe Northgate Rebellion sets off the Gilnean Civil War. 
**The Scythe of Elune comes to Southern Elwynn Forest. After becoming overrun by worgen and other demonic threats the region becomes known as Duskwood, with the town of Grand Hamlet becoming Darkshire. /
**Explorers' League is founded. 
*Year 23 - Silvermoon City is rebuilt seemingly over-night by the magic of the Magisters. 
*Year 24 - Tensions between Alliance and Horde rise again.
**The Forsaken join the Horde at the behest of the tauren, primarily Hamuul Runetotem and later Magatha Grimtotem. /
*Year 25 - World of Warcraft begins.
**King Varian Wrynn of Stormwind is kidnapped, and his son Anduin Wrynn is temporarily crowned. The black dragon Onyxia is discovered in Stormwind City. An assault is launched on Blackwing Lair, home of the black dragon Nefarian. 
**The Argent Dawn is formed.
**In the deserts of Silithus, the qiraji launch an invasion at the behest of the Old God C'thun. Kel'thuzad launches an attack on Azeroth from the dread citadel Naxxramas in the Eastern Kingdoms.
**The Scourge begin training Death Knights in Acherus for an assault on the Scarlet Enclave.
*Year 26 - The Burning Crusade. /
**The Dark Portal is rebuilt and re-opened by Lord Kazzak, and both Horde and Alliance forces travel to Outland. There the orc Garrosh Hellscream is discovered by Warchief Thrall, and taken back to Azeroth to act as an adviser.
**Prince Kael'thas Suntrider of the blood elves allies with the Burning Legion, attempting to summon the demon lord Kil'jaeden to Azeroth. He leads the blood elves within the Outlands to attack the draenei, causing them to flee upon a small ship called the Exodar (sabotaged to crash by the blood elves) with a few of the naaru. /
**After meeting the night elves and hearing their tales of the Alliance, the draenei are inspired to pledge their allegiance. /
**The blood elves of Quel'Thalas join the Horde. 
**The Aldor and the Scryers are formed in the remnants of Shattrath thanks to the Sha'tar, which subsequently leads to the formation of the Shattered Sun Offensive. /
**M'uru is abducted by the blood elves and the Blood Knights seek to use the naaru's life essence as a replacement for the Sunwell's power. After much time and once M'uru is offered freedom, the naaru sacrifices itself to restore the Sunwell. 
*Year 27 - The Wrath of the Lich King.
**The Lich King launches a new assault on Azeroth, attacking Stormwind City and Orgrimmar. Alliance and Horde forces both travel to Northrend to combat the Lich King. Garrosh Hellscream is sent to lead the Horde forces in Northrend. /
**Third generation Death Knights lead to the fall of the Scarlet Enclave, and are later freed of the Lich King's influence at Light's Hope Chapel. Those that choose to organize for the common good form the Ebon Blade, allying with the Alliance and Horde.
**After the battle at Light's Hope Chapel, the Knights of the Silver hand merge with the Argent Dawn to form the Argent Crusade.
**The Lich King is defeated, replaced by the sacrifice of Bolvar Fordragon.
*Year 28 - The Cataclysm. /
**Thrall steps down from his position as Warchief and appoints Garrosh Hellscream as the new leader of the Horde as he leaves to travel the world to assist with the elemental unrest. 
**The former Dragon Aspect Deathwing is driven mad by the Old Gods and bursts through into Azeroth from the Elemental Plane, shattering the surface of the world as tensions between the Alliance and Horde continue to build.
**Arugal's worgen spring free and attack the city of Gilneas. After a brief albeit viscous struggle, a temporary cure is found by the Apothecaries of Gilneas, allowing infected worgen to regain some form of humanity. Night elves land upon Gilnean shores to offer their aide, feeling responsible for the spreading curse and assist with a more permanent cure for the worgen feralism. Gilneas and the worgen join the Alliance, staying in Darnassus with the night elves. //
**The Forsaken forces focus their wartime efforts upon the city of Gilneas, employing a dangerous plague and resurrecting the dead that they can. //
**Gallywix tricks the Bilgewater goblins into giving all of their life earnings to him before causing the destruction of their island. The Bilgewater Cartel joins the Horde. 
**The Elemental Lords Ragnaros and Al'Akir are slain, as well as Cho'gall, leader of the Twilight Cult. The Dragon Aspects expend the last of their power to kill Deathwing, and the Age of Mortals begins.
*Year 30 - The Invasion of Pandaria. 
**All-out war erupts between the Alliance and Horde when Warchief Garrosh Hellscream destroys the city of Theramore with a mana bomb. Archmage Rhonin dies, and Lady Jaina Proudmoore takes his place as leader of the Kirin Tor, a council of some of Azeroth's most powerful magi.
**Pandaren residents of the Wandering Isle ally with both the Alliance and Horde after a ship crash lands into Shen-zin Su and the continent of Pandaria is discovered. 
**Jaina forcibly removes the Horde from Dalaran after the Sunreaver faction creates portals to allow for a Horde invasion upon the Alliance. The magocratic city-state's support is thrown behind the Alliance. /
**The sha are released on Pandaria, and the Thunder King Lei Shen is resurrected. 
**Garrosh orders the assassination of the Darkspear leader, Vol'jin. Vol'jin begins the Darkspear Rebellion, pitting Horde against Horde. The Alliance covertly assists the Darkspear rebels, seeking to end Garrosh's reign as Warchief. /
**After a rigorous battle for Orgrimmar, the sha-corrupted Garrosh Hellscream is captured and sentenced to trial in Pandaria. After an unknown line of events rumoured to be spear-headed by the last Black Dragonflght whelp named Wrathion, Garrosh is freed from his imprisonment.
*Year 31 - The Iron Horde Rises.