I found the entire ESO official backstory if anyone is interested and wants to read it…
Strange things are happening all over Tamriel. The dead stir in their graves; zombies and darker creatures congregate more and more frequently in every corner of the land. Winters grow colder and crops fail. Mystics are plagued by nightmares and portents of doom.
These events began with the Soulburst, in 2E 579, four years before present. An arcane explosion in the Imperial City set off aftershocks in every corner of Nirn. Mages died or went mad. Disasters and freakish weather lashed every province of Tamriel. Red Mountain flared and trembled in Morrowind, earthquakes shook Skyrim, and massive storms devastated the coastlines of Elsweyr and Valenwood. The constellation of the Serpent reappeared in the skies and grew so large that it seemed to threaten every star sign at once.
Unbeknownst to all but a few, Nirn has come unmoored from the fabric of the multiverse, as the mortal realm is drawn ever closer to Coldharbour, the twisted Oblivion realm of the Daedric Prince of domination and enslavement, Molag Bal. The Planemeld, a process in which the two worlds slowly become one, is threatening the existence of all races on Tamriel.
Eruptions of darkness have appeared in Nirn where one can step directly from Tamriel into Coldharbour, and they are spreading. Nirn is being drawn toward Coldharbour by Dark Anchors, powerful magical objects embedded in Tamriel’s surface. Each death in Tamriel weakens the barriers between worlds. With war erupting throughout the continent, the Planemeld is accelerated, bringing the Daedric Prince’s scheme closer to fruition.
The Imperial City, and with it, the throne of Tamriel, is controlled by Molag Bal’s followers. Necromancy has been declared legal in the Empire, and the Arcane University – once home to the Mages Guild – has been turned over to the necromancers of the Worm Cult.
The Daggerfall Covenant is rocked with undead uprisings, Valenwood and Elsweyr are invaded and form an alliance with Summerset, and an unlikely pact forms in the north and east between Black Marsh, Morrowind, and Skyrim. The three alliances take up arms against the Empire and each other, each trying to take control of the Imperial City and White-Gold Tower.
The Daggerfall Covenant was founded in Wayrest, High Rock, in 2E 567, uniting under the High King Emeric. The Daggerfall Covenant is a traditionalist alliance, seeking to re-establish the Second Empire and return Tamriel to peace and prosperity.
Though historically enemies, the three races united when the Breton King Emeric of Wayrest came under attack after marrying a Redguard princess from the Hammerfell state of Sentinel. Rallying the Redguards of Sentinel and enlisting the help of the Orcs, Emeric defeated his foes and repaid his allies by fulfilling promises made to them. The unification behind King Emeric led to stability in the region. While many Redguards remained wary of the Bretons, and even refused to join the Daggerfall Covenant, it is the strongest of the three alliances, bound by a desire to restore peace and prosperity to Tamriel.
The Bretons are the political masters of the Covenant, charismatic negotiators and traders. They are also the undisputed magic and wizardry experts of the alliance, naturally in touch with environmental and elemental manipulation.
The Redguards hail from the Hammerfell cities of Sentinel and Hallin’s Stand. They are the smallest of the three races in terms of numbers, but they make up for it with their tactical brilliance on the battlefield.
The Orcs are bound to the Daggerfall Covenant by honor after having King Emeric’s promises fulfilled. The Orcs believe the Bretons have earned their loyalty and fight viciously against the Covenant’s opponents. The Orcs are the Covenant’s toughest infantry and most talented smiths, forging strong weaponry and scattering all those who stand against them while standing next to the Redguards and Bretons on the battlefield.
The Aldmeri Dominion is newly formed, the youngest of the alliances born in response to recent events and ancient pacts. The Altmer of Summerset lead the Dominion, motivated to take control of the Imperial City in order to restore Elven rule to Tamriel and wipe out the forces of Molag Bal that hold the throne and the White-Gold Tower.
The alliance, though new, is already tenuous. While the three races don’t openly quarrel with each other, each feels attacks on its own homeland must take priority. Valenwood, home of the Wood Elves, is under attack by Colovian Imperials from the southwest of Cyrodiil. Their forests are being razed and burned, and as a result, the Bosmer are stretched thin. Meanwhile, the Khajiit face invasion into Elsweyr by Nibenese Imperials who are seizing the fertile grasslands where the Khajiiti’s herds graze.
The Altmer of Summerset are the Dominion’s leaders. While they are the political heads of the Dominion, due to their tradition of isolationism they are also the least numerous. Reluctant to leave Summerset, few High Elves can be found on mainland Tamriel. Nonetheless, they guide the Aldmeri Dominion’s strategic vision, leading the campaign to restore Tamriel to Elven rule and end the tyranny of the Empires of Men.
The Bosmer play a strategic role in the Aldmeri Dominion’s survival. The de facto capitol of the Dominion, Elden Root, lies in the heart of Valenwood, and is the logistical heart of the alliance. From Elden Root, forces spread out towards Cyrodiil, guided by the Altmer. However, not every Bosmer tribe is fully committed to the Dominion because of the threat currently in their homelands, but they provide an invaluable service, guiding the Khajiit and Altmer through their dense, near-impassable woodland home. They fight to evict the invaders from Valenwood and as a result, accept the aid of the Altmer and Khajiit to do so.
The Khajiit owe a great debt to the Altmer, who came to their aid when their population was suffering from the Knahaten Flu, and saved many of the Khajiiti people. The Khajiit see the Dominion as a means to setting the world right and saving themselves from future invasions and wars. They are the strong arm of the Dominion, the backbone of the alliance’s military, rushing to meet their enemies with glee, instilling fear wherever they go.
The Ebonheart Pact is the most extraordinary and fragile of all the alliances in Tamriel. Born out of necessity, it is an alliance forged between three groups whose deep-seated, bitter sentiments and distrust for each other is barely outmatched by their shared animosity for the races they have allied against. But they respect each other as only old enemies can.
The most geographically far-reaching of all the alliances, the Ebonheart Pact spreads across the northern and eastern rims of Tamriel. Though such a large area of control would usually promote discord amongst allies, in the case of the Ebonheart Pact, it strengthens their alliance. Each race has so much territory of their own to deal with that they have no desire to meddle in each other’s lands. Like the other alliances, the Ebonheart Pact hasn’t existed for long. It was formed ten years before present, in SE 572, when the Second Akaviri Invasion ravaged northeast Tamriel. Nord, Dunmer, and free Argonians fought as one, saving Tamriel from slavery and subjugation. The fierce enemies allied to form a new power, ruled over by the Great Moot, a council of equals from all three races.
The Nords once conquered most of Tamriel, and as a result, feel a certain entitlement to rule. They broke the power of the Ayleids, nearly drove the Altmer out of High Rock, and ruled much of Morrowind before the arrival of the Dark Elves. Strong warriors, the Nords face battle with an ecstatic ferocity that terrifies their enemies.
The Dark Elves are a proud race that is excellent at diplomacy, subterfuge, and tactics. Their magical abilities and long history of fighting off external threats has prepared them for this great fight for Tamriel. Invaded again and again, they trust no one, but put their best warriors and sorcerers into the fight, led by the living gods of the Tribunal, who abide among them.
The Argonians have suffered from millennia of slavery at the hands of the Dark Elves. They are possessed of a cool intelligence, and are well-versed in the magical arts, stealth, and the use of blades. They are guerrilla warfare experts, accustomed to defending their borders from larger forces, and as a result, they serve as the scouts and skirmishers of the Pact armies.
Now, faced with enemies from across Tamriel and from Oblivion itself, the allies fight to save all of Nirn. This is Tamriel’s most desperate hour. With whom will you take up arms?