(Dark tag for prejudice and abuse themes in T story)
(Human stays human and is not the lead character)
It is four hundred years before the Unification of the three pony tribes and founding of Equestria. The events that prepared the three tribes began by chance, long before the idea of Harmony was even believed possible.
It is a time when Earth ponies struggle against abuse, exploitation, subjugation, and sometimes even outright slavery.
Unicorns and Pegasi regularly take their food, leaving them struggling to survive each winter. When an Earth pony gains their mark in something of value, they are often stolen away, forced into labor for the rest of their lives. Their treatment by other races is rarely better. Most are worse, if not outright deadly.
Pegasi, with their wings and weather control, can strike anywhere. Unicorns and their spells can lay them low from a distance. Their few free towns and cities never remain so long enough to develop any means with which to fight back. They have ideas, but learning is always stolen or destroyed with each raid. Each generation struggles just to maintain what has been, hoping to find a new way.
Then came the day a village, four years into a new subjugation, found a strange wounded biped known to them only by tale and legend shortly after a Unicorn visit took much of their food yet again one mid-winter. Unwilling to let him die in the cold even with so little to share, they take him in.
With a sign from the gods and the stranger's knowledge, one mare and her village begin to see a chance to finally break the cycle and be free.
Art of the main character, Quiet Grace: https://wilvarin-liadon.deviantart.com/art/Quiet-Grace-702726048
Editing help from: stupidhand14
A side story and ancient history in the same verse as my main story, Protecting Harmony. Timeline of the verse places the events of this story roughly around 4000 years in the past. The specifics of why are complicated in this intricate and expansive verse. Initial expected length was once projected under 50k words. However, considering the sheer volume of stuff I need to do, I have recognized it's not going to be enough. I have a terrible capacity for thinking up more stuff to add to something of this nature on top of it. 
Initial inspiration came from listening to this thematic musical score: Chinese battle music - Xian
I had a moment of pondering what made Unicorns and Pegasi see Earth ponies as equals. About what makes the Earth tribe such an equally vital part of the triad and what those qualities are.
This story is the result.
To a certain extent, I am drawing from my understanding of the natural tendencies of humans and other species expressing preferential bias towards those like themselves, be it in family groups or up to the species as a whole. In ancient times, humans were quite brutal towards just rival nations visually identical to themselves. Where things like differences in skin color came into play, I don't think anyone needs to be reminded of how much worse it could get.
Cover image is more a Protecting Harmony verse placeholder. Might be a long time, but I eventually intend to see a post-chapter 1 image of a defiant Quiet Grace on this story. I have a lot of images in this verse to seek out surrounding my main story already.
