A term used for the largest of invasions of the underground inhabitants in Tal' Dorei.
They forced the kingdom to work together to defend themselves, promoting unity.

The first Quaking happened before royal records. Dwarves of the below, in their greed, dag up too high and breached the surface.
The myths speak of a time when the earth grew empty and the Dwarves scorched the surface, recovering all the metal they could.
On their Quest for the Sky, they displaced another people - the Orcs. They were pushed to the surface by the Dwarves and decided to carve themselves a kingdom in the vast forests of Tal' Dorei.
Nowadays both people live in peace on the Isles surface, however the first Quake was a reminder of the necessity of unity - for the Darklands are vast and always eager to swallow everything they touch.

The second Quaking lasted from year -32. until year 16
This invasion lasted nearly fifty years and consisted of several waves of different invaders pushing for their space under the sun.
In 01.01.0 the invasion fleet of the Kingdom of Horugva reached the Isles and settled on the border of Tal' Dorei.
While preoccupied with the second quake, Tal' Dorei didn't want to risk a two-front war. That is why they made an accord with the new kingdom, gifting a part of their lands to Horugva while establishing trade and a non-aggression pact.

The third Quaking lasted from year 1079. to year 1101. This Quaking was unique because it didn't start as a war, but a migration crisis as numerous creatures moved to the surface. They were escaping the Serpent wars that captured most of the second layer of the Darklands in this region. The war eventually spilled into Tal' Dorei, partially because it was harboring the refugees.
Eventually the wars quieted down and Tal' Dorei was left with a unique mix of inhabitants, marking the kingdom even today as a safe haven for the underground races willing to cooperate.

The fourth and newest Quaking lasted from 26.04.1451 until 11.09.1472.
This period was marked with the neighboring Kingdom of Horugva starting a war in the Isles. This quake preoccupied Tal' Dorei enough that hey couldn't participate even if they wanted to.
This Quake was fought primarily against the Orv nation Dominion of the Black - a conglomeration of psychic conquerors capable of controlling others. Some of their most powerful allies included the mating pair of dragon rulers of the Midnight Mountains: The Umbral Archdragon Kazan and the Elder Wyrmwraith Lelek.