(year 1908) Tensions with Griffonstone have been rising again for decades, and they come to a head when the griffons invade Rainbow Falls and move towards Trottingham and then to Fillydelphia. A war with Griffonstone has officially started.
(year 1911) Scarlett dies in a battle with the griffons, and Periwinkle takes over. Peri is young and inexperienced, and Equestria quickly surrenders, leaving the griffons Trottingham and Rainbow Falls and the mountains surrounding it. Equestria and Griffonstone don’t really officially consort with each other after that.
(year 2001) Calliope dies of old age. (Just like Orpheus, she lives longer than normal, especially for a pegasus, and she turned down the opportunity to become an alicorn. She didn't want to deal with learning unicorn & earth pony magic later in life. She’d rather just enjoy what she already has.)
(year 2019) Peri adopts their one year old niece, Stella (a unicorn) when Mayleigh and her husband die in a fire, and he raises her as his own daughter.
(year 2046) Periwinkle dies in a tragic train crash, which kills 9 ponies, including the conductor, and injures 17, and Stella takes over. However, it makes a lot of ponies uneasy. (Peri planned to turn Stella into an alicorn after she’d been trained for a while, and she was sure she was ready and wanted it, but they died before they could, and now there are no more alicorns.) Stella is a pretty good ruler, despite being rather young, but Equestria has never had a non-alicorn as a ruler, and especially the earth ponies and pegasi are unhappy.
(year 2112) Stella retires and dies a few months later, she appoints one of her advisors, Dust Storm (who’s an earth pony, age 42), as the next ruler. Ponies are a bit more comfortable now with the situation, but the unicorns are now experiencing some stress and uncertainty.
(year 2137) Dust Storm dies of cancer at a time of turmoil with the yaks, and he appoints his military advisor, Thunderclap (pegasus, age 33), as the next ruler. War with the yaks occurs under Thunderclap’s rule. The war ends in a stalemate eventually, but the ponies are more divided than ever, especially when two more pegasi rulers follow after Thunderclap, his sister Lightning Strike and then her daughter, Gentle Rain. Not much happens under their rules, but ponies are mad that the Pegasi seem to have taken over the monarchy.
(year 2244) After Gentle Rain, her son, Castor (an earth pony, age 32), becomes the new ruler, which cools the earth ponies’ anger a bit, but the unicorns are even worse.
(year 2294) After Castor, his niece, Dara Dawn (unicorn, age 49), takes over, and then her daughter, Nymphadora (unicorn, age 43) takes over after her.
(year 2377) After Nymphadora, her nephew Florian (unicorn, age 31) becomes the next ruler. Three unicorns in a row, making the other ponies, whose anger had been cooling, riled up again. The unicorns in turn get angry back at them for “being distrustful.” The tension between tribes is the highest it's been since pre-Equestrian days, and the wendigos are peaking their heads in a bit.
Dark Ages:
(year 2393) Florian is suddenly assassinated (sparks the Dark Ages), by an unknown pony (the mystery is still unsolved), before he names an heir. The ponies riot without a ruler. What’s left of the government frantically tries to introduce candidates for leadership, but it’s too late. The wendigos have resurfaced. The ponies are already living in mostly segregated cities and towns, and now they’re fighting with each other all the time - about food, weather, lighting & heating spells, etc.
(year 2397) Discord steps in and decimates the wendigos and tells the ponies to get their shit together, and then he disappears back to his realm. He’s very upset that the ponies are stomping all over Fluttershy’s legacy.
(year 2408) The ponies’ fighting goes on until finally, without the wendigos, the spirit of the Tree of Harmony uses the rest of its remaining magic and the leftover wendigo residue to store all pony magic in three crystals, one given to each tribe. They only work if they’re all brought together, but each tribe is too proud and angry to meet and try it.
Ponies don’t really record everything for a while, as they get used to living without magic (weather running wild, planting & growing crops without magic, none of the spells that kept houses warm & lit, the trains going, etc.) Everyone (almost) pretty much forgets about the crystals holding their magic.
(year 2501) Spike dies of old age.
(year 2712) The three tribes have each mostly settled in their own places and stop communication with each other. There’s no more trains or any large transport system, so it’s not too hard. The main three cities are Maretime Bay (earth ponies), Zephyr Heights (pegasi), and Bridlewood (unicorns), but there are smaller settlements of each tribe scattered around the remnants of Equestria. Some of them are integrated, but only barely. Eventually these become pretty much totally segregated as well.
There are some historians who try to recover and remember the past, but most want it left forgotten.
