Void Era: Catch-all term for anything before 500; everything here is just myths and fairytales.

Light Era: 500-2100; events of the show and the bulk of its history

Current Era: 2100-2150; the time the roleplay takes place

Two thousand years ago - or so the equine legends go - there were two; Sun and Moon. Between and beyond them there was more: stars and planets and comets. But these two were the only things that lived. They talked to each other often, for they had nothing else to do, and one day the Sun thought that she might want another companion. She created the first pony, white with a flowing rainbow mane, which she placed on the nearest planet. The Moon, fascinated, did the same, but she could not capture the essence of what Sun had made. Hers was blue and small, and while her mane shone like the stars, it was different from Sun's.

They befriended their creations - Celestia and Luna. And the two ponies made more: they had magic, and neither Sun nor Moon objected to them creating fheir own companions.

But never mind myth; let us focus instead on fact.

It was around 500 that the first known records were kept, although the original copies have been lost to time. Ponies, it seems, were and still are the slowest to adopt new technologies - which is compensated for in many other areas, like medicine and botany.

Equestria was founded in 510; the Hearth's Warming Eve episode elaborates on the story. It was soon after that the Celestial Sisters made themselves known, having thus far been in hiding, only occasionally appearing to grant the ponies aid in difficult situations. Their reign was short-lived, though - about forty years passed before Discord came about, and just after that came Nightmare Moon.

A thousand years passed, and then began the events of the show, with a small change. When Twilight gave up the Elements of Harmony to the Tree, this did not solve their problems. It took the Elements, then swallowed their bearers, leaving Equestria at the mercy of the plunderseeds for five years. Even Discord was unable to stop them without great loss, but he came through in the end, at the cost of his own life.

So began the Current Era. (Soon to be renamed, most likely.) The seeds have vanished, with the sun and moon beginning to have taken on their own order, but that was the extent of the repair. Nearly every building and structure has been destroyed; the changeling queen has died, leaving her subjects roaming the land; few remain after the plunderseeds destroyed all.