Last week, I detailed what I was able to glean from the entire run of My Little Pony 'n Friends. How can we use this information? Well, it's pretty obvious this is not a part of Equestria taken literally. The base rules of the world are different, with a larger variety of sentient creatures, cutie-marks and unicorn magic working differently, and so on.
However, this is the series that inspired Lauren Faust as she developed Friendship is Magic, and several of the things from this series have already been translated to Equestria. So that means we can steal from this setting and migrate it into Equestria as long as we're sufficiently liberal with our interpretations.
If we were to force the issue, the various valleys and volcanic mountains would best map to the western coast of Equestria, covering a relatively small area somewhere between Tall Tale and Los Pegasis in the Unicorn Range. In fact, it may be the reason for the city name of Tall Tale, which given the pony's penchant to puns would have been more likely to be called Tall Tail normally. Possibly it's named after the mythology of Dream Valley that the legends place near by. In which case we may be dealing with an prior expedition of ponies crossing into Equestria long before the one mentioned in the Hearth's Warming Eve episode. This would be similar to the Norse settlements in Newfoundland that occurred in the 10th century which had died out and had been forgotten long before the rest of Europe started showing up in the 15th century.
The variety of other sentient creatures is the hardest to deal with. Where did they all go, between the time of G1 and G4? If the time-frame of North America above is any guide, we're dealing with at least 500 years, which is not enough for that number of intelligent species to simply disappear without deliberate action on behalf of *somebody*. That's proper fanfiction fodder right there. If you take the series in a different order, and have the Theatrical movie actually happen at the end of the historical events rather than near the beginning, you do have the devastation of the Smooze to work with. It's not inconceivable that the low populations of all the other races meant that the Smooze event dropped them below the minimum viable population.
That aside, here are some examples of things we can steal:
First, pony culture itself. In this series, mares and stallions are heavily segregated, and foals are raised by the community not by their parents. This can easily be true in the past for Equestria, and may even explain why the show gives the impression that the ratio of stallions to mares in Equestria is so oddly skewed. It may only be relatively recently that the nuclear family concept has become the norm in this society, as in within the last thousand years or so. Hearts and Hooves Day may actually be Celestia trying her hoof at social engineering, rather than how Valentines Day was created in the real world, all in an effort to increase the population growth of her little ponies.
The Seaponies may yet exist, but have retreated to the deeper seas. Flutterponies... I'm being told that alternate versions of the flutterponies exist in one of the later series, but I haven't reached them yet, so I'll leave them for now.
Second, the antagonists. Let's only deal with the heavy hitters here; Squirk, Grognar, and Tirek. The various witches, like Hydia and Catrina, are actually pretty generic and don't need much in the way of adaption.
Squirk is a horribly silly name, but the concept of an ancient Kraken that wants to flood the world to claim all that territory as it's own, is perfectly sound and can be made *really* creepy. His main power source, the Flashstone, already has an analogue in FiM, in the Alicorn Amulet. An amulet that allows the wielder to use massive magic power with little to no limits.
Grognar is a wonderful mythological villain. The Ram Sorcerer, who made a necklace that allowed him to channel and control the power of the Bell of Tambelon. The story of the lost city of Tambelon itself has so many mythological precedents, and likely has some kind of a connection to the capitol of the Crystal Empire. Possibly being Sombra's inspiration for doing that trick.
And then there's Tirek. As I mentioned in my essay on the Terror of Tartaurus, he's a bit trickier to use as some of his shtick was transferred to Nightmare Moon. However, he is unique in that he used his transformative power on unwilling targets, rather than be a shapeshifter himself. Adding in that he may have been cursed by his own power, and his natural form may have been quite different (perhaps a normal minotaur), and you have an interesting villain there.
Finally, let's look at the artifacts. I've already mentioned the flashstone, but there are a few others that are interesting. The Dark and Light Rainbows, for example. Two paired yet opposite powers. One forcing metamorphosis on unwilling victims, and the other restoring things to their true form. Given the effect of the Elements of Harmony is normally shown as a Rainbow, it's possible they are connected and the Rainbow of Light is inhabiting the Elements of Harmony due to some events that were not shown in the series.
The Sunstone is interesting, perhaps being one of a pair of artifacts that allowed the Unicorns of Hearth's Warming Eve to control the sun and moon before Celestia and Luna came along. The other being the Moonstone, of course. Maybe these things are still around in a vault in Canterlot, and some unicorns decide to use it in an attempt to overthrow the princesses...
The six crowns of the Heart of Ponyland could very well be the first known versions of the Elements of Harmony. Normally linked to the Crystal Heart, they were separated by ponies wishing to protect them from those who would abuse their power, and scattered across the land. It was these legendary artifacts that Starswirl devoted so much time to. Later Celestia and Luna take Starswirl's research as a guide to re-assemble them as part of their Hero's Quest to defeat Discord. In this version, they would take on Sombra *before* Discord, attempting to recover the final piece, the Crystal Heart itself. Sombra phased the entire capitol of the Crystal Empire, using the same dark magic as the Lost City of Tambelon. The Princesses could not retrieve the Heart, and they had to take on Discord with a not-quite-complete set.
I've left the Smooze until here, because it's... odd. It was summoned by a spell, and appears at least partially self-aware and 'alive'. But honestly that's not that much different from the variety of artifacts in the series. But it's considerably more dangerous than any artifact; a true weapon of mass destruction, who's only real weakness is the stupidity of the witches who put it into play. Those who survive the Smooze are still affected by it, driven to sickness and depression. To be honest, for how silly it was being portrayed, this thing has the highest potential for GrimDark in the entire G1 series, even more than Tirek, Grognar, and Squirk combined. When you look at it a bit closer, and take off the rose-colored glasses, the Smooze is very much a biological equivalent of a nuclear weapon, complete with radiation sickness and the like, leaving only complete devastation in it's wake.
Oh, and the connection between the pony world and the human world. Allowing for Equestria Girls' rather odd coloration being an artistic choice rather than 'reality', it lines up rather nicely with the time passing between contacts getting shorter an shorter from the human world's perspective. It does mean that the calendar of the human world is completely disconnected to the calendar of the pony world, which means Luna's mention of 30 moons was actually only vaguely relevant to Twilight, as it would have been 30 moons in the pony world, but who knows how long in the human world.
There are lots of other small details that could be ported over, but as they are truely tiny details I think I've done enough for this essay.