Eldia

"My daughters. Give birth and multiply. The blood of Ymir must not die out. If you die, my daughters, have my grandchildren eat your spines. If my grandchildren die, their spines will be passed from child to child. To all of my progeny. My Eldians will rule the lands of this land with their massive frames. And my Titans will continue their reign. Into eternity, so long as this world of mine remains."

- King Fritz proclaiming Eldia's rule over the world for centuries to come. "Eldia was a great and ancient nation that destroyed Marley and came to rule the continent. That is when the Dark Ages began."

- Mr. Yeager teaching Grisha Yeager about Eldia's past.

Eldia was an incredibly powerful empire that ruled the world for thousands of years in the Attack on Titan universe. While it is currently the faction of the protagonists of the story, it is clear that its past incarnation as the Eldian Empire was a cruel and pivotal villainous faction that was responsible for a great deal of the tragedies in the world, including the creation of the Titans.

Past
2000 years ago, a girl named Ymir gained the power of the Titans, becoming the first Titan to ever walk the earth. Seeing her potential, the leader of the Eldian tribe, Fritz, used her to build bridges across mountains, cultivate barren lands and build roads. Pleased with the progress that his people were making because of Ymir, the Eldian ruler "rewarded" her by forcing her to bear his children, who would latter be named Maria, Rose and Sheena. He also ordered her that, in his name, he should crush the nation of Marley with her massive Titan form. 13 years of war between Marley and Eldia caused the utter submission of the former and the rise to power of the latter. As the leaders of Marley were beginning to bow before King Fritz, one man suddently drew a spear with the intent to end the infamous Eldian King who brought so much destruction and terror to their nation. Ymir, however, willingly put herself in the spear's way and saved the tyrant's life. This resulted in King Fritz forcing his daughters Maria, Rose and Sheena to inherit their mother's power by cannibalizing on her, which resulted in turn in the creation of the Coordinate and, eventually, the rise of the Nine Titans who would terrorize the world of centuries to come. In time, eight noble houses were formed to inherit eight of the Nine Titans (Attack, Colossal, Cart, Female, Jaw, Beast, War Hammer, and Armored Titans) to rule Eldia under the supremacy of the Fritz royal family and their Founding Titan, who acted as the Kings of Eldia.

The Eldians used the Titans as weapons of mass destruction to conquer other nations, wiping out countless cultures in the process, and it was said that they pursued mass rape as a conquering method to give birth to more Subjects of Ymir to turn into Titans. It is estimated that the number of people the Eldians have slaughtered is over three times world population of year 854. Allegedly, Marley was once again victim to Eldia's warmongering around 1,200 years ago, when Eldia assaulted Marleyan cities during the "Fall of Lago," the "Devastation of Monte," and the "Ravaging of Valle." Survivors from the Fall of Lago fled into the wastes, but were caught by Titans who had been awaiting their retreat. However, the historical validity of these Eldian attacks against Marley are a matter of debate.

Around the year 240, the Subjects of Ymir within the Eldian Empire were spared from widespread death from a worldwide epidemic through the actions of the King of Eldia. Using the power of the Founding Titan, the Subjects of Ymir were altered in their biology, rendering them immune to the disease. At some point in later history, the Eldians made allies with Hizuru.

Eventually, the Eldians ran out of enemies and began fighting each other. The eight noble houses that ruled Eldia entered in a state of conflict, but the Fritz family maintained order with the Founding Titan.

Around year 738, the Founding Titan came into the possession of Karl Fritz, the 145th King of Eldia. The King believed that Eldia's sins couldn't be atoned for, and that Eldians and Titans should not have existed in the first place. He pitied the Marleyans and devised a plan alongside the Tybur family, one of the eight noble houses and the keepers of the War Hammer Titan, to end the Eldian rule. The King abandoned the internal conflicts, and without the Founding Titan to keep order, the Eldian Empire collapsed. The Eldians fought and weakened themselves during the Great Titan War, while the King and the Tybur family presented the legend of Helos, a Marleyan hero who joined with the Tybur family to defeat the King. The Tybur family fought to restore Marley in the war; other noble families would evidently follow suit. They succeeded and Marley gained seven of the Nine Titans as a result. The King moved the capital to Paradis Island, Eldia's last remaining territory, and gathered as many Eldians he could on the island.

Once on Paradis Island, the King used the Founding Titan to cause Colossus Titans to form three concentric Walls around their territory: Maria, Rose, and Sheena. Afterward, Karl Fritz changed his family's surname to "Reiss" to conceal his identity and put a puppet "Fritz" family in the throne while he and his family masqueraded as mere nobles (but remaining in secret the true royal family and the ultimate authority of the Walls). He also used the Founding Titan once more to erase the Subjects of Ymir's memory of the Great Titan War and all of history before the raising of the Walls. For the next century, the Subjects of Ymir in Paradis Island lived on in peace, unaware of their past conflicts, their history as the Eldians, and the world outside the Walls.

On the mainland, the Eldians who did not flee to Paradis Island were conquered by Marley. Marley spared these Eldians, who became second-class citizens. They were forced to reside within internment zones, such as Liberio's, separate from the Marleyan population.[25] Marley used their new influence to spread slander of the Eldian Empire, claiming they had resorted to eugenics against the other races of the world for 1,700 years and that Ymir Fritz had gained her power from the "Devil of All Earth." Any Eldians accused of committing wrongdoing against the Marleyans were sent to "Heaven" in Paradis Island and turned into mindless Titans, doomed to wander for eternity outside the Walls.

Coup de état and the basement
In year 850, after more than a century of ignorance, a military uprising, led by the commander in-chief Darius Zackly, commander Dot Pixis of the Garrison and commander Erwin Smith of the Survey Corps, managed to overthrow the Royal Government and it's fake king, exposing the government's lies to its own people and putting Historia Reiss, Rod Reiss' daughter and the true heir to the Kingdom of the Walls, in the throne.

Two months after the coup, the Survey Corps led by Erwin Smith executed a massive operation to take Shiganshina District in order to reach Grisha Yeager's basement, which was said to contain the secrets of the world. While the operation nearly ended in failure, they ultimately succeeded in reaching the basement, but almost all of the Survey Corps, including their commander, were wiped out by Zeke Yeager and his Warriors.

The revelations of the basement were shocking for both Paradis' civilians and the military, as they discovered that they were hated by the rest of the world by the past crimes that the Eldian Empire committed against Marley, that the coup de état was only possible due to Grisha Yeager's usurpation of the Founding Titan and that they were a century behind the rest of the world in terms of technology so there is no chance for them to defend themselves if the world decides to attack them unless they use the "Rumbling" superweapon which consists in the awakening of the tens of thousands of Colossal Titans inside the Walls with the power of the Founding Titan that dwells in Eren Yeager.

The arrival of the Anti-Marleyan Volunteers
In year 851 a marleyan survey fleet arrives Paradis Island. While the crew of the fleet arrived to scout the area, they were betrayed by a group of traitors known as the Anti-Marleyan Volunteers led by a woman named Yelena and make contact with the Eldians of Paradis. While the revelation that they were working for their old enemy, Zeke Yeager (who claimed to want to see Eldia restored and that Historia should eat him to become the next Beast Titan of royal blood in order for Eren successfully use the Founding Titan), caused the members of the military to mistrust the Volunteers, they concluded that, being the most hated nation in a world that was practically unknown to them, they had no choice but accept the help it was offered. Ultimately, the Volunteers make a deal to help Paradis Island with covert diplomacy, technological transfer, and intelligence gathering in exchange of granting Zeke and his followers amnesty in the Island. The plan to test the "Rumbling" weapon, keeps being postponed time and again, however.

The Raid on Liberio
In year 854, Willy Tybur makes a speech internment zone of Liberio to unite the world against the "Island Devils" of Paradis. However, immediately after Tybur finished his speech, Eren Yeager turns into the Attack Titan and eats him. He then begins to destroy the place in order to kill all of the officials from the Marleyan Military in hopes of dealing a fatal blow to it. After that, the War Hammer Titan shows up and engages Eren in a brutal fight. Meanwhile, the Survey Corps, armed with anti-personnel gear modified by the technology provided by the Anti-Marleyan Volunteers for the last 3 years, storm the ghetto to defend Eren, and marleyan soldiers prove to be no match for them; only Marley's Titan Warriors can successfully face them. After a brutal fight, Eren manages to eat the War Hammer Titan with the help of Mikasa Ackerman and the Survey Corps begin their retreat in a stolen Zeppelin, taking Zeke and the Volunteers with them.

The second coup de état
Back on Paradis, Eren Yeager is put into prison for insubordination, the Volunteers are all put into house arrest under suspicion for conspiracy and Zeke Yeager is taken to a Titan Forest by Levi Ackerman.

However, a group inside the military called the "Yeagerists" led by Floch Forster begin to spread the rumors of Eren being arrested to the civilians of Paradis, which causes a mass-scandal and makes the military loose it's popularity. When a manifestation against the military government was taking place in Stohess District, the Yeagerists plant a bomb in Darius Zackly's office and manage to assassinate the commander in-chief. Roughly at the same time, Eren Yeager escapes from prison using the power of the War Hammer Titan. Eren and the Yeagerists then reveal to the remaining military officers that Zeke's spinal fluid was in most of the wine they drank in the last month and forced them to cooperate with him.

Eren takes most of the remaining Survey Corps to Shiganshina and puts them into the local military HQ's prison, while a group of Yeagerists led by Floch use Hange to get to Zeke's position. Meanwhile in the Titan Forest, Zeke and Levi engage in battle, with Levi initially beating and capturing the former but ultimately failing and being caught in a Thunder Spear explosion caused by Zeke. While Hange takes a dying Levi and throws herself in the water to escape, Zeke regenerates from the harm caused by the Spear and meets the Yeagerists, who agree to take him to Shiganshina were Eren is located.

Surprise attack on Shiganshina
In Shiganshina, Marley's weakened military and it's Warriors launch a desperate surprise attack on Paradis in order to take the Founding Titan from Eren and end the threat of the Rumbling. A massive battle ensures, with Eren fighting the combined forces of Reiner, Porco and Pieck, with the former two constantly trying to steal the Founder. Meanwhile, the Eldian anti-Titan and anti-personnel forces clash with Marleyan soldiers who are more prepared to face them now with anti-Titan rifles. The prisoners Eren took from the Survey Corps also join the fight shortly afterwards. While Eren is fighting the Warriors, Zeke suddenly on the Wall and begins to assist Eldia's forces by throwing rocks at their Zeppelins and assisting Eren against Reiner and Porco. However, Pieck manages to shoot Zeke's nape and the Beast Titan begins to fall from the Wall into the ground. Eren then rushes onto Zeke but before he can make contact with him, he is shot in the neck and his head separates from his body, falling into Zeke's open hand.

Because Zeke watched Eren before he could fully die, Eren reaches out to Ymir inside the Coordinate and pleads her to lend him her strength, claiming that the choice was her's alone whether to stay in that world forever or put an end to it. Ymir is deeply touched by Eren's words and begins to cry, granting him the full power of the Founding Titan.

Eren then begins to regenerate and a massive spinal cord emerges from his head as he begins to transform into a Titan while Wall collapses and the Colossal Titans inside it are awakened, initiating the Rumbling.

Trivia

 * The ancient Eldian tribe may have been inspired by the Norse society of old as it resembles Norse aesthetics and warrior culture.
 * The relationship between the Marleyans and the Eldians features many real-world reflections of Nazi Germany and the Jews. Like Jews living in pre-WWII Nazi Germany, the Eldians live in segregated ghettos, forced to wear star-emblemed upper armbands to distinguish them from non-Eldians, suffer severe discrimination with frequent comparisons to demonic entities, and face constant calls to be exterminated. The Germanic-traits of the culture as well as most of Marley's and Paradis Island's inhabitants reinforce these strong similarities.
 * The history of Marleyans and Eldians is also partially comparable with that of the Rwandan populations of Hutu and Tutsi. By 1700, the Rwandan populace coalesced into around eight kingdoms, of which the Tutsi Kingdom of Rwanda became dominant and oppressed the Hutu, fueling a hard relationship between the two races that lasted for centuries. In 1994, during the Rwandan Civil War, the then Hutu majority government perpetrated a genocide against the Tutsi which resulted in the extermination of around 70% of the Tutsi population.