Fictional chronology

The franchise's media provides riches of historical information.

Equestria before show time
Parts of the history of Equestria, the homeland of ponies, are known; mainly from the show.

The foundation of Equestria
In the episode Hearth's Warming Eve, Spike – as the narrator of a pageant – tells that "long before the peaceful rule of Celestia, and before ponies discovered [...] Equestria, ponies [...] were torn apart, by hatred. [Each] of the three [pony] tribes, the Pegasi, the unicorns, and the Earth ponies, cared not for what befell the other tribes, but only for their own welfare."


 * "[The] Pegasi were the stewards of the weather. But, they demanded something in return"...
 * ..."Food, that could only be grown by the Earth ponies."
 * "The unicorns demanded the same, in return for magically bringing forth day and night"...

..."And so, mistrust between the tribes festered, until one fateful day, it came to a boil. And what prompted the ponies to clash [was] a mysterious blizzard that overtook the land, and toppled the tribes' precarious peace."

The episode then shows a very harsh winter coming to the land, forcing the ponies to discuss an agreement to unite all forces. The summit ends up a catastrophic failure. After that, the three tribes' leaders, each accompanied by one subordinate, venture to find a new land to establish their tribe upon.


 * Commander Hurricane, accompanied by Private Pansy, founds Pegasopolis on a cloud, for the Pegasi;
 * Princess Platinum, along with Clover the Clever, names a spot she finds "dazzling" Unicornia, for the unicorns;
 * the Earth ponies' Chancellor Puddinghead calls their new found land Dirtville before changing it to Earth, following the advise of her right hand, Smart Cookie.

One problem immediately appears: these three places are steps away from each other, and it is not long before each of the leader claims their rights on the biggest possible portion of territory to separate from the others.

The place is then surrounded by terrible blizzards in minutes, which forces the six ponies to find shelter in a nearby cave. There, the leaders continue their disputes. These are soon frozen alive, and the three subordinates express to each other their compassion.

When the three remaining ponies are in turn frozen, a surge goes through the unicorn Clover the Clever. Her horn generates a giant fiery heart shape, the Fire of Friendship. This warm light quickly frees everyone from the cold, and banishes the cause of the blizzards, the hatred-fed Windigos.

The six ponies representing the three tribes then meet outside the cave, where they declare the foundation of one common country under the name of Equestria.

Discord
The Princesses are not mentioned in the story above, from the episode Hearth's Warming Eve. Their first known appearance happens later in the show's storyline, more than 1000 years before the show's time, against Discord.

"This creature is called a 'draconequus'. He has the head of a pony, and a body made up of all sorts of things."

- Cheerilee, in the episode The Return of Harmony Part 1

In the episode The Return of Harmony Part 1, Princess Celestia tells that "Discord is the mischievous spirit of disharmony. [He] ruled Equestria in an eternal state of unrest and unhappiness.

Luna and [Celestia] saw how miserable life was for Earth ponies, Pegasi, and unicorns alike; so after discovering the Elements of Harmony, [they] combined [their] powers and rose up against him; turning him to stone".

Celestia then explains that she then "though the spell [they] cast would keep him contained forever". It is not explained if the Princesses were already princesses at that time, nor if they already controlled the sun and moon.

At the beginning of the episode, Cheerilee's class sees the petrified Discord in Canterlot's sculpture garden, and Cheerilee says it is a "statue [representing] Discord, which means 'a lack of harmony'".


 * #↓ Aftermath

The Crystal Empire


The Crystal Empire is a region of Equestria, but according to Princess Celestia in the episode The Crystal Empire - Part 1, very little of its history is actually remembered.

In this episode, it is made clear that the Crystal Empire's most valuable magical relic is the Crystal Heart, which channels the light and love within the Crystal Ponies to repel evil forces.

To this end, the Empire's first queen established the annual Crystal Faire, which would become the Crystal Ponies' most cherished tradition. The purpose of the Faire is to "renew the spirit of love and unity in the Empire so [the Crystal Ponies] could protect it from harm".

At some point in the Crystal Empire's history, a "Crystal Kingdom Anthem" is written; as mentionned by Twilight Sparkle in the episode.

Princess Celestia tells that sometime in the Empire's past, its ruler was overthrown, and an evil unicorn stallion named Sombra took over as king. She says that he subsequently enslaved the Crystal Ponies, and his influence transformed the Empire into a dark land and covered it in black crystal spires. The Princess continues, explaining that she and her sister, Princess Luna, eventually overthrew Sombra himself, turning him to shadow, and banishing him under the ice of The North.

However, Princess Celestia finally reveals that King Sombra had a contingency plan: a curse that caused the Crystal Empire and its population to vanish into thin air, suposedly indefinitely.


 * #↓ Aftermath

Nightmare Moon
The pilot episode Friendship is Magic, part 1 starts with the following narration: "Once upon a time, in the magical land of Equestria, there were two regal sisters who ruled together, and created harmony for all the land. To do this, the eldest [, Princess Celestia,] used her unicorn powers to raise the sun at dawn; the younger [, Princess Luna,] brought out the moon to begin the night. Thus, the two sisters maintained balance for their kingdom and their subjects, all the different types of ponies.

But as time went on, the younger sister became resentful. The ponies relished and played in the day her elder sister brought forth, but shunned and slept through her beautiful night. One fateful day, the younger unicorn 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 ponydom: the Elements of Harmony. Using the magic of the Elements of Harmony, she defeated her younger sister, and banished her permanently in the moon. The elder sister took on responsibility for both sun and moon..." "...and harmony has been maintained in Equestria for generations since." finishes Twilight Sparkle, student and protégée of Princess Celestia.


 * #↓ Aftermath

"A little less than 1000 years go by, between the above events and the ones below."


 * In the episode The Cutie Mark Chronicles, the main characters recall how Rainbow Dash's first sonic rainboom ever caused more or less directly them to gain their cutie mark.

Season 1

 * 1) In the episode Friendship is Magic, part 1, Twilight Sparkle participates in an Apple family reunion.


 * #↓ Next occurence

The Mare in the Moon
The episode Friendship is Magic, part 1 reveals that the banishment of Nightmare Moon was not permanent, and would end after a thousand years. Coincidentally, the last day of the millenium comes two days after when Twilight Sparkle reads the book.

Two days after, "the stars [...] aid in her escape", and Nightmare Moon is released from her imprisonment on the moon. Upon return, in Friendship is Magic, part 2, Nightmare Moon claims her legitimacy to the throne of Equestria, while Princess Celestia is amiss.

The main characters finally defeat her, which makes her disappear. All that is left of her are smoking shredded pieces of her armor, and Princess Luna, under a different appearance. Celestia returns at this moment and reunites with her sister, offering her to rule with her, as was "meant to [be]".


 * #↑ Prelude
 * #↓ Aftermath

The return of Discord
To understand what comes next, here is a short reminder of the franchise's storyline related in the episodes Friendship is Magic, part 1, Friendship is Magic, part 2, The Return of Harmony Part 1, and above.

In the episode The Return of Harmony Part 1, Princess Celestia tells that she and her sister Luna discovered the six items known as the "Elements of Harmony" more than 1000 years before the show's time, making them their oldest known historic holders.

In the episode Friendship is Magic, part 2, Twilight Sparkle reads that "the last known location of the five elements was in the ancient castle of the royal pony sisters [, Princess Celestia and Princess Luna,] located in what is now [the] Everfree Forest". The royal castle used by Princess Celestia, at that episode's time in the show, is situated in Canterlot. The episode also shows how the main characters become the bearers of the Elements of Harmony at that time; which happens some time before the events of the episode The Return of Harmony Part 1.

In the episode The Return of Harmony Part 1, Princess Celestia continues her story where it was cut above; at when her and her sister Luna turned Discord to stone. At the time of the episode, "since Luna and [her] are no longer connected to the Elements of Harmony", due to them being connected to the main characters since the episode Friendship is Magic, part 2, "the spell [was] broken".

Indeed: in the beginning of the episode, Discord is accidentally freed from petrification by arguing children.

The Princess then attempts to retrieve the Elements of Harmony, which she had hidden in Canterlot Tower since their last use in the episode Friendship is Magic, part 2.This to give them back to the main characters, in order for the ponies to use the artefacts to turn Discord into stone once again. However, she doesn't find them and Discord makes it clear that he had displaced them beforehand, avoiding Celestia's move. He then tricks five of the six bearers to render them harmless.

In the episode The Return of Harmony Part 2, the draconequus turns Ponyville into his "chaos capital of the world" by messing with much of its features in chaotic ways. He eventually breaks the will of the last active Element bearer, Twilight Sparkle. The Princess then succeeds in bringing her student back to her quest thanks to Twilight's assistant Spike. The unicorn then regains the aid of her five fellow Elements, who finally turn Discord into stone again at the end of the episode.


 * #↑ Prelude
 * #↓ Aftermath

The return of the Crystal Empire
King Sombra's spell, as related above, was not definitive. In the episode The Crystal Empire - Part 1, more than 1000 years later, Princess Celestia sends the main characters to the Crystal Empire, which has apparently returned.

Upon arrival, they learn that King Sombra has somewhat returned too. in The Crystal Empire - Part 2, Twilight Sparkle and Spike manage to find the Crystal Heart, which Sombra had hidden in the capital city castle's paramount spire when in power; and manage to return it to its stand, where the heart immediately regains its power from the Crystal Ponies' confidence. The Crystal Heart then bursts in energy, which destroys Sombra, and frees the Empire from the harsh conditions he had brought back with him.


 * #↑ Prelude

 In the episode Magical Mystery Cure, Twilight Sparkle mixes up the cutie marks of her friends, wrecking havoc in Ponyville, and causing them deep pain. She finds a solution, succeeding in her final student's test. Having created new magic, she is consequently turned into an alicorn, accompanied by Princess Celestia, and crowned Princess Twilight Sparkle. 

Here ends the historical part about Equestria as of the end of Season 3.

Buffalos
In the episode Over a Barrel, Chief Thunderhooves of the Buffalos, near Appleloosa, tells the story of how his tribe has lived in the same place for generations, and how he sees that the pony settlers arrived one year before are invaders, especially with their misplaced apple orchard.

The moon
The history of the moon is not richly explained in the show.

In the episode Hearth's Warming Eve, it is explained that before the Princesses ruled over Equestria, it was the unicorn tribe which was in charge of raising and lowering the sun and moon.

In the episode Friendship is Magic, part 1, it is told that from an unknown date up until about a thousand years before the show's time, Princess Luna, bearing a crescent moon as her cutie mark, raised the moon and stars to begin the night, and lowered them to make place for the day her sister, Princess Celestia, brought forth by raising the sun.

When she turned into Nightmare Moon, she was banished to the satellite for a millenium. During this period, Celestia took over the charge of the moon cycle. After these ten centuries, she came back to Equestria, became Princess Luna again, and it is assumed that she got back her power over the astre.

In the second arc of IDW Main Series comics, the nightmarish power which had enslaved the princess threatens Equestria again. When Luna and the main characters go to the moon to stop it, it takes control over Rarity. It is the occasion to get to know more about this place which has been under the malefice of this nightmare for an undetermined period of time.

The main six finally destroy the vilain entity and free the moon's denizens, as well as Rarity's spirit, and Luna, from her fears.