Prior to the explosion of the Skystone, Etherea was inhabitable and not covered in Haze. Mimics did not exist.
20 BH (Before the Haze)
The Paydirt Tramway is built by the original inhabitants of Deadrock Canyon.
0 AH (1800 CE)
The Skystone explodes, starting the AH (After the Haze) era. Haze begins to cover the land and Mimics begin to appear.
0 AH is equivalent to 1800 CE.
At this point, 25% of the land is covered with Haze and is uninhabitable. This causes the Great Displacement, a large exodus of refugees from Haze-filled areas to Haze-free areas.
The Battle of Blueridge begins. The Ferrics and the Crags fight for control of the Blue Ridge River, a major source of fresh water and commerce.
The Battle of Blueridge ends. The Ferrics and the Crags sign a treaty that ends the conflict.
Admiral Chivington signs the Ferric Removal Act, starting a campaign to remove the Ferric tribes that inhabited the foothills of the Cedervale Mountains.
Nidaria takes flight, and most of Etherea's residents move there.
Crags use the Paydirt Tramway to flee to Nidaria.
At some point, there was an Etherite Rush. A year after the Etherite Rush, Aeronauts declared war on the Crags living on Grittop Mountain. The Aeronauts wished to gain control of the mountain, which had unusually high amounts of Etherite.
- This information is taken from the Development Blog post on Nidaria. A Skystone 101 Sprocket states that Nidaria was built in 5 years.