The Founders of Equestria
Long ago, before the rise of the alicorn sister Princess Celestia and Princess Luna, the pony tribes were often at odds with each other and often stuck to their own tribes. When a mysterious blizzard began to affect their way of life, the three leaders and their second-in-commands set out to find new land.
The three leaders begin to fight over the new land, causing another blizzard to occur. After being trapped in a cave, the three leaders are soon frozen in ice by Windigos, the cause of the blizzards and winter spirits that feed off of hatred.
Upon putting their differences aside, the second-in-commands are able to fend off the windigos and unfreeze the leaders. Hence, equestria was born.
Princess Platinum Platter: The only daughter of King Bullion. She was still very young when her father fell very ill and she was left to assume the crown. Platinum was originally very flighty and snobbish, and slightly out-of-touch with her struggling subjects. It wasn't until she was saved from the windigos where she learned about true and genuine friendship. While still a little bit snobbish, she went down in history for her generosity as well as for the creation of the Grand Galloping Gala, which is still celebrated to this day.
Clover the Clever: The star pupil of Star Swirl the Beared as well as Princess Platinum's royal advisor. Being the apprentice to such of an important spell caster, Clover had access to a wide variety of magic spells. Following fending off the windigos, Clover dedicated herself to her studies where she became a staple of sorcery.
Commander Hurricande Thunder: The leader of the pegasus tribe. Hurricane was very militaristic short-tempered. He went down in history for founding Equestria's military system.
Private Violet Pansies: Commander Hurricane's younger sister and subordinate. Also known as Private Pansy, Pansy was a very meek mare who would rather play with bunnies instead of shinning her armor. Useless in battle, Hurricane had her practically in a secretarial position: anything to keep her out of combat. After fending off the wendigos, she went down in history for the foundation of the Winter Wrap Up.
Chancellor Pudding Pie: The elected leader of the earth pony tribe. A very eccentric and excitable stallion, just not to the degree that Pinkie Pie's portrayal was. Those who disliked him often called him "Puddinghead".
Smart Cookie: Pudding Pie's secretary and close friend. Smart Cookie was basically Pudding's voice of reason. While history often portrays them as being married...history is not always accurate. She went on to revolutionize farming through out the nation of Equestria.
Gusty the Great and Grogar
Thousands of moons ago, prior to the existence of Equestria, Grogar was a ram who lived in a cave just outside of the unicorn's homeland of Unicorna. Initially, Grogar kept to himself as he practiced his magic. At first, the unicorns left Grogar alone. Unbeknownst to them, Grogar was transforming the other animals into monstrous beasts, which in turn began to terrorize the unicorns. It wasn't long until unicorns started going missing...
Gusty Gale was an orphaned unicorn who existed during the time of Unicorna. For reasons unknown, she found herself alone in the wilderness outside of Unicorna. Here, she was found and even taken in by Grogar, a mysterious ram who lived in a nearby cave.
Gusty showed real promise with magic, which made Grogar end up taking her on as a student. The more magic she learned, the more powerful she got. But as time went on, she became shocked by her mentor's usage of dark magic. And when Grogar began turning her fellow unicorns into monsters, she rebelled against her teacher.
The unicorns tried to get rid of him but Grogar was too powerful for them. Things seemed to be lost until he was betrayed by his ex-student. Grogar battled his ex-student and a group of unicorns she rallied together. Since he couldn't be defeated, his ex-student out-smarted him and stole the source of his power: The Bewitching Bell. He was weakened without the bell and was ultimately sealed in his own cave.
Knowing that he wouldn't be trapped forever, his ex-student hid the bell away in an enchanted cave on a Mt. Everhoof.
Ponies and Magic
In Equestria, there are three main pony types: earth ponies, pegasi, and unicorns. Much like all other creatures, the three pony types all have magic stored in their bodies but depending on the pony type, the magic is stored in different places.
Earth Ponies: Earth pony magic is stored in their hooves which can be challenged into growing plants and crops. This is why so many earth ponies are in farming or agriculture. Earth pony magic also has the side effect of making earth ponies the strongest of the three main pony types in terms of physical strength. This is why so many earth ponies are in physical labor such as construction or pulling carriages.
Pegasi: Pegasus magic is stored in their wings, giving them the ability to fly and walk on clouds. The magic pegasi possess allows them to alter the weather such as being able to move clouds or creating weather-related wakes when flying. This is why most pegasi have jobs in weather control.
Unicorns: Unicorn magic is stored in their horns, making them the only main pony type able to actively peform magic, being able to levitate or move objects or cast spells. Prior to Celestia and Luna, unicorns were the ones responsible for raising the sun and moon.
The Prophecy and Celestia's Students
Shortly after Luna's banishment, Princess Celestia learned of a prophecy: when the stars aligin to finally let Nightmare Moon, a unicorn of immense power would use the elements of harmony to restore Luna. A unicorn who would ascend to alicornhood and lead Equestria and beyond into a new age of hope and friendship. A unicorn that she would personally take under her wing as her personal student.
Over the centuries, Princess Celestia would come across many powerful unicorns that she took under her wing with all of them not working out such Sunset Shimmer who was power hungry and fled to the human world or Sunburst who, while very knowledgeable about magic, had a disability that made him struggle with casting powerful spells and led to him running to the Crystal Empire in shame.