Subject of Ymir
The Subjects of Ymir are descended from Ymir Fritz herself, the first human to acquire the Founding Titan over 1,800 years ago. After Ymir's demise, her daughters Maria, Rose, and Sheena Fritz devoured her corpse and gained her ability to turn into Titans. As per their father's commands, Ymir's daughters reproduced to expand their bloodline and continue the race of humans who can turn into Titans.The power of the Titans eventually split into Nine individual Titans and The Subjects of Ymir used them to conquer the old nation of Marley along with Pure Titans.Following this they established the Eldian Empire, which over the centuries would come to rule the mainland continent of its origin.
About 600 years ago, an epidemic plagued much of the world; killing so many that the population plummeted. The King at the time used the power of the Founding Titan to rewrite how the bodies of the Subjects of Ymir were designed to overcome and survive the pandemic.
The rule of the Eldian Empire lasted until the end of the Great Titan War, which resulted in Marley's resurrection as a nation and Eldia's capital being moved to Paradis Island.The 145th Monarch Karl Fritz used the Founding Titan to turn thousands countless of his Subjects into Colossus Titans, commanding them to form three concentric Walls surrounding the land surrounding the new capital of Eldia.On the mainland, Marley gathered the Eldians, and placed them into internment zones such as within Liberio. They were spared eradication due to their ability to be turned into Titans for war purposes, as the Eldian Empire had done during its reign.On the island, the Subjects of Ymir had their memories of the world outside the Walls erased by the Founding Titan.
The Eldians of other races were unaffected by the Founding Titan, so the royal family either granted them the privilege of living inside Wall Sheena in exchange for their silence, such as the fake Fritz family,or persecuted them as in the case of the Ackerman and Azumabito families.Other countries around the world also placed Eldians into internment zones; the treatment of Eldians in those countries is far worse than the treatment of Eldians in Marley.