Equestria-Earth Timeline

Synopsis
 The Equestria/Earth timeline is as follows: 

Beginning: Both worlds were not widely populated, Earth was peopled sparsely and many animals covered the land, Equestria was divided and populated with many creatures.

Several centuries leading up to 1700 BC, Equestria underwent a dramatic change, the Keepers were summoned to that world and began to bring order and peace; the creatures that refused to relinquish their control to the Keepers were banished to Asteria the underworld. Earth was beginning its first powerful civilizations.

1700 BC: The First Era: Reign of the Keepers began/First human-equestrian contact through the Bifrost.

900 BC: Mudan, Keeper of Change, becomes the Spirit of Discord/Unicorns disappear from Earth, legends of Equestria spread.

100 AD: Discord is defeated, the Triad Era begins/Britain, bastion of the Old Religion, is tamed by Rome, druids and Celts resist Roman rule, many flee to Equestria.

1008 AD: Luna is exiled/The dark ages continue on Earth.

2010 AD: Luna returns/MLP FIM airs in the US.

Additional Information
Some ponies went to live with the humans of Earth and some humans even lived among the ponies of Equestria. Suppose that the “beginning” of both Equestria and Earth are the same, and then suppose that time passes in roughly the same rate. First contact between the Equestrians and humans would have been around 1700 BC.

 Eventually, active encounters became isolated events in key parts of the world. These being the locations of the surviving Yggdrasil trees. As complex civilizations developed, their populations turned to science and logic. They saw less need for magic and the arcane. This caused the magic to fade from the region, this magic is what sustained the Yggdrasil. Without it they die. This is how subsequent contacts were reduced to a few places on Earth. As the Yggdrasil died so did the Yeodoor on the other side of Bifrost.

 The last interaction between Earth and Equestria was around 510 AD. The Turoten was constructed in AD 515 or so and sent to Equestria. Shortly after the death of the last Yggdrasil, the time known as the “Dark Ages” Began on Earth.

Graphical Timeline
The map of Equestria depicted in the bottom half of this timeline was created by Henrik Lissner.