The beginning: From the fic Paradise by SlyWit.

Gen 1 ponies existed slightly before Discord's reign.

During Discord's rule, the new found civilisation collapsed, reducing ponies back to tribalism, until Celestia and Luna brought law and order back.

Years (about 100-300 years) before the founding of Equestria, there was an empire called the Roaman Empire which were ruled by Pegasi. Anyone living outside the empire were considered 'savage barbarians' (even Pegasi). Ironically, they were more brutal than Hurricane's pegasi.

Ancient (about 100 and more years before the founding of Equestria) Earth Ponies had druids and shamans as their priests and mages.

Unicorns are patriarchal by nature unlike other pony tribes and had kings as their dominant rulers of their kingdoms.

During its peak of power, the Crystal Empire was a rival to its southern neighbour, the Roaman Empire. It also had a shaky relation to its other neighbour, Kingdom of Gryphonia too.

The Roaman Pegasi could only conquer a small part of the Everfree Valley (Everfree Valley: the area where there is the Everfree Forest and Ponyville) and had to build the Everfree Wall to stop Earth Pony and sometimes Unicorn barbarians invading their empire.

Discord's Game

My Little Alicorn

The Return of Princess Nightmare Moon

Paradise

The Three Sisters