@Starswirl  
You know, if you’d gotten that time travel spell working, you could have gone far enough into the future to see Star Wars and realize you were on the verge of reliving (pre-living?) it.

If you assume that Celestia and Luna had kept themselves hidden after the defeat of Discord, having decided to let the others run things on their own for a while, then you can almost make this fit. Sombra was the unicorn king, who enslaved everyone from his seat in what was eventually named the Crystal Empire. Platinum was the heiress apparent, and found Clover, whose company she found enjoyable, but once the cold times came around, the Pegasi and Earth Ponies rebelled, leaving the cold lands for warmer climes. Platinum was sent out as well, with the rest of the unicorns to find new lands for Sombra’s empire, leaving only the crystal ponies, who were less worn out by the cold, to remain. By then, Celestia and Luna had heard enough about Sombra to use the elements to destroy his mortal form and seal him in the ice. Sombra managed to hide the empire for 1000 years, and Celestia and Luna began to search for any pony life out there. That was when the three tribes came across one another, and old rivalries and bitterness resurfaced. Some time after everything was over and Equestria was formed, Celestia and Luna made themselves known, and were surprised to find themselves crowned the High Princesses of Equestria when they rose the sun and moon on their own. Luna would eventually turn bitter over being ignored and stage a coup, but that’s another story.

Oh god, cute sombra. Fav’d

Now there’s a thought.

King Sombra confirmed for awesome father

I will neither confirm nor deny that this is precisely what happened; that Sombra was my first apprentice; that he went completely power crazy after he looked into my Crystall Mirror while it was set on Grogar’s castle; and that I taught Clover to have somepony on the inside.
 
Nope, nothing to see here.

Awww… Isn’t that cute? She wants her own slaves to just like her Daddy…

So Sombra might be older than Luna and Celestia

“I don’t know, a wizard is a big responsibility. You’ll have to feed her, walk her, keep her from summoning eldritch horrors from beyond space and time…”  
“Pleeeeeease.”  
“Oh, I can’t say no to that face.”  
“Yay!”  
“But if all of existence is consumed, it’s your fault.”  
“I love you too, Daddy.”

Now I’m sad that Rarity is not actually SOmbra’s daughter. Because she could make that work.

I was just thinking this last night.  
Both love crystals and shit

Them being related is cool, but Sombra being the child makes more sense.

I can see this being a thing.

“Oh course you can sweetie, now daddy has to go now. He has to stop those Earth ponies from thinking, you know how they can hurt themselves with that.”

Unicornia was a province of the Crystal Empire ruled by Princess Platinum while her father King Sombra ruled the empire proper.
 
After Sombra became evil, the heart of the empire vanished leaving the provinces on their own. Platinum retained leadership of what was left of Unicornia while the other provinces would get absorbed into Pegasopolis and the Earth Pony REpublic.
 
Cue Windigos.

Hang on a second… King Sombra post dates the rule of Celestia, while Platinum predated it. And he ruled the Crystal Empire while she was from Unicornia.
 
That said, I could see Sombra being descended from her.

Pffft, sure wynaut

 
This is the best idea ever.

D’aaaaaawwwwww.