Skyrim is the fifth game in the Elder Scrolls series, but it doesn’t tell you much about its backstory. Not in obvious ways, anyway. After all, how would you rather start a game: with a history lesson, or with dragons setting people on fire?
Still, if you've spent a hundred hours in Oblivion or Morrowind, it's only natural to wonder what's happened to your old stomping grounds. That information is scattered throughout Skyrim's books and dialogue, but with no frame of reference, piecing all the events and dates together can be daunting. To give you some foundation, here's a summary of what's happened since you last visited Tamriel.
The first thing you need to know is that 200 years have passed since the events of Oblivion. That's the biggest time jump in the Elder Scrolls series so far. For instance, Oblivion took place a mere 34 years after the first Elder Scrolls game, 1994's Arena.
(Conveniently, Tamriel's fourth age started when the Oblivion Crisis ended, so years in Skyrim are counted from the end of the Oblivion. If a history book says something happened in 4E33, that's about 167 years before Skyrim's present day.)
Above: Here, you're going to need this
Over these two centuries, the Empire has started to crumble. When Martin Septim sacrificed himself to end the Oblivion Crisis, it left the 400-year-old Empire without an emperor. The empire's hold over its territories began to slip.
One of these territories was Summerset Isle, home of the Altmer (aka high elves). During the Oblivion Crisis, Daedra poured through the dimensional gates and massacred its inhabitants. Then, just when everything seemed hopeless, the invaders simply disappeared.
A faction called the Thalmor, elven supremacists and all-around jerkbags, claimed credit for the miraculous disappearances. They said they closed the Oblivion gates with subtle magics. In fact, they were so subtle that nobody saw them doing it. A grateful population hailed their new heroes, and by the time people started to wonder if they'd been suckered, the Thalmor had consolidated their power and squashed dissent.
Over in the Imperial heartland of Cyrodiil, things weren't going so well. High Chancellor Ocato, the acting ruler during and after Oblivion, was assassinated before any new emperor was elected. (One Altmer dissident claims the Thalmor were behind it, but no one knows for sure.)
Above: "Wait, what?"
The provinces of Black Marsh and Elswyr, homes of the Argonians and Khajiit, seceded from the Empire. But of all the provinces, Morrowind got it the worst.
Morrowind players probably remember Vivec, ruler of Morrowind and subject of endless volumes of Kim Jong-Il-esque propaganda about how he was a living god who kept the forces of evil at bay by his will alone. Unlike Kim Jong-Il, that turned out to be mostly true.
Visitors to Morrowind probably also remember the Ministry of Truth, a rock floating above the capital that was used as a prison. The Ministry was said to be a meteor that Vivec froze in time before it struck the city. This also turned out to be true.
Above: This doesn't end well
With Vivec having lost his godhood after the events of Morrowind, the Ministry eventually snapped back into time and slammed into Vvardenfell with all the force it originally had. Vivec City was obliterated. The Red Mountain erupted from meteor strike, destroying the island of Vvardenfell. Waves from the impact swamped the rest of Morrowind.
The Argonians, justifiably angry about being enslaved by the Dunmer (aka dark elves) for generations, invaded what was left of Morrowind from the south. Dark-elf refugees filtered into Skyrim, settling in the slums of Nord cities like Windhelm.
After seven years of bloody infighting for the Empire's throne, a Cyrodiilic warlord named Titus Mede had seized power with a mere thousand warriors. His descendants ran things up to the time of Skyrim, and they're responsible for there still being an Empire at all.
Meanwhile, the Thalmor backed a coup of the Bosmer (aka wood elf) home of Valenwood. Empire forces and loyalist wood elves were defeated, and Valenwood fell. The Thalmor named their territory the Aldmeri Dominion, after the pre-Empire elven nation.
So, the end result of the first 50 years after Oblivion was a weakened Empire and a powerful, independent nation of scheming jerk elves. That set the stage for The Great War, the aftershocks of which defined the world of Skyrim.
Above: Jerks
In 4E171, An Aldmeri ambassador rolled up to the Imperial City with a covered wagon and a list of demands for Emperor Titus Mede II. The Empire was to cede large chunks of Hammerfell, disband the Blades, and stop worshipping Talos. (Talos is the first emperor, Tiber Septim, who allegedly ascended to godhood. He had steamrolled the old Aldmeri Dominion with a borrowed dwarven weapon of mass destruction, and the Thalmor weren't fans.)
Emperor Titus II refused, and the ambassador dumped the contents of the cart. It was the heads of every Blades agent spying in the Aldmeri Dominion. The war was on.
The Aldmeri invaded Hammerfell and Cyrodiil, and over several years, they advanced until the Imperial City itself was surrounded. Titus II's army fought its way out of the city to link up with reinforcements from Skyrim, and the elves sacked the Imperial capital. The palace was burned and the White Gold Tower, the most recognizable landmark in Oblivion, was looted.
The Thalmor thought they had won the war, and Titus II encouraged them to think that, all while planning a counterattack. The attack, called The Battle of the Red Ring, took the elven forces by surprise and completely crushed them, thanks in no small part to Nord reinforcements from Skyrim. The Imperial City was in the hands of Imperials again.
Even though the Aldmer forces in Cyrodiil were destroyed, the Imperial armies were in no shape to continue fighting. Titus II took advantage of the victory to negotiate a peace treaty.
The White-Gold Concordat, negotiated at the namesake tower, didn't seem great for the Empire. It disbanded the Blades, ceded occupied Hammerfell to the Aldmeri, and outlawed the worship of Talos. In short, it was everything the Aldmeri ambassador had asked for before he redecorated the throne room with Blade noggins.
Titus II believed that granting these terms after fighting to a standstill was better than having just given in in the first place. Giving in would have meant a civil war in the Empire, but at the time of the treaty, all the territories wanted an end to the fighting.
Still, the Concordat left territories like Hammerfell and Skyrim feeling betrayed. The Redguards of Hammerfell rejected the treaty and fought the Aldmeri Dominion for five more years, eventually driving them out and making a second peace treaty necessary.
Many Nords were outraged at the outlawing of Talos worship. Tiber Septim was a Nord, and the cult of the first emperor was popular in Skyrim. Many soldiers from Skyrim died to retake the Imperial City, and the White-Gold Concordat seemed like a betrayal. The Nine Divines may have officially become the Eight Divines in the Empire, but many Nords kept the faith. (Also, if you pray to Talos, all your diseases are cured. So there's that.)
So, at the beginning of Skyrim, the Aldmeri are taking the long view, waiting for the Empire to weaken and fall apart from within. The Empire is biding its time, trying to recover its strength so it can oppose the Aldmeri. Many Nords think the Empire is no longer strong enough to protect Skyrim. A Jarl by the name of Ulfric Stormcloak has just paid a visit to the high king, and a certain prisoner is on his way to be executed...
And that, is the history behind skyrim.