In the beginning, there was nothing, and all was filled with emptiness. This emptiness was called Void. However, the Void would not last forever, for all things could not remain the same forever.
No, that would be boring, and Pinkie Pie doesn't like boring stories. And so Pinkie Pie imagined, and created the universe. Looking upon her creation, she saw that it was interesting, and she was pleased. Yet Pinkie Pie was not satisfied. She wanted more than that, and so she brought forth stars and planets from the universe.
Looking over her many worlds, she chose one, calling it Earth. She gave it a shining yellow sun to twirl about, and set it just so in its orbit - not too far, but not too close, either. Finally, all was ready: Pinkie Pie swirled about the oceans, and life was born. For many millions of years, she carefully guided the evolution of that life, creating dinosaurs (they didn't pan out, so she got rid of them and tried again) and snakes and leopards and all manner of creatures. One creature, she decided, she would create in her own image, and that creature was the pony.
However, Pinkie Pie does not have patience spanning an eternity, and grew distracted. The intelligence she had intended for her beloved ponies was bestowed instead on one of her less successful experiments, a species which could barely survive at all. The hairless apes, or humans, as they called themselves, spread over the planet.
For many thousands of years, she watched over her creations, tolerating the accident of the humans. She watched as they developed civilizations, growing and competing with each other. She watched as they created religion, venerating their creator, if through a misguided image. She watched as the civilizations grew, and began to war amongst themselves. This did not please her, but she allowed it, in hopes that it would pass.
There were many solutions that she tried, in her attempts to redeem her creations. She created new lands, so that the humans wouldn't have to fight over what they had, with new foods and new cultures. But the new cultures were beaten down, and the new lands became prizes to be fought over.
The wars grew ever more violent, and the weapons they used grew ever crueler. Finally, Pinkie Pie had to admit it. This was what she had made.
She could not be satisfied by this. It wasn't enough. And so, Pinkie Pie made the waters rise, covering the land, and wiping away the creatures of the world. And so, Pinkie Pie began anew, and created the intelligent ponies she had intended so long ago. She created the dragons, and the griffins, and the diamond dogs.
She watched over these new creations, and they pleased her. Pinkie Pie smiled upon them, and all was well, for many long millennia. But again, Pinkie Pie became distracted, and her creations discovered war. From the chaos they created, Discord was born, and he wreaked havoc over the world. Also chocolate rain, which met with Pinkie Pie's approval. However, she knew that her ponies could never be happy under Discord's rule, and so she regretfully arranged for him to be defeated and imprisoned in stone.
For many years, all was well, and the ponies prospered. However, as the centuries passed, the races grew apart from each other. Pinkie Pie watched carefully, sad that her favorite creations had found the same fate as had the humans so long before. The pegasi squabbled with the unicorns, who in turn fought with the earth ponies. And so, she created the windigos. They fed on the ponies' hatred, covering the land in ice. Eventually, the pony species split apart and went their separate ways.
Pinkie Pie did not approve. She had created the three races to work together, not fight, and not ignore each other. And so, with some small degree of hope left, she led them all to a new land, untouched by ice and hatred, none of them knowing of the others' presence. She watched as they each lay claim to the same land, and fought once again. She watched, sadly, as the leaders of each race became encased in the ice of their hatred. Pinkie Pie turned her back then, and wept at the loss of her beloved ponies to the ice she had created to destroy them. She had hoped that it might be enough to unite them again, but it was not.
It was then that she saw it. A gentle glow of warmth. Three ponies, one of each race, united in friendship. She watched, a smile slowly growing across her face, which had not smiled in so long, as the three ponies sang songs and told stories through the long night. Pinkie Pie has never been more proud of her little ponies than she was on that cold night.
Yet, she knew that even though these ponies would be friends, and perhaps their children, that friendship could too easily fall apart. And so Pinkie Pie created two special ponies, with all the traits that made each species unique. The elder, she named Celestia, to watch over the day. The younger, Luna, was to watch over the night. The two sisters would create harmony for all the land.
For millennia, it worked just as she had hoped. Unfortunately, it was not to last. With all the other traits of the three pony species came flaws as well. As time went on, the younger sister became resentful. The ponies relished and played in the day her sister brought forth, but shunned and slept through her beautiful night. One fateful day, the younger sister refused to lower the moon to make way for the dawn. The elder sister tried to reason with her, but the bitterness in the young one's heart had transformed her into a wicked mare of darkness: Nightmare Moon. She vowed that she would shroud the land in eternal night.
Reluctantly, the elder sister harnessed the most powerful magic known to Ponykind, the Elements of Harmony. Using the magic of the Elements of Harmony, she defeated her younger sister and banished her to the moon. The elder sister took her responsibility, both sun and moon, and harmony was maintained in Equestria for many generations.
Almost a thousand years passed, and Nightmare Moon would soon escape from her lunar prison. Pinkie Pie finally decided it was time to intervene directly. And so she entered her own creation, in the form of a young, pink earth pony.
The rest, I think, you already know.
