The Age of Shadows

The Age of Shadows on Magicians' End begin in 4290 APC after the dramatic fall of the government of the Second Popular Ascendancy and lasted for more than nine hundred years until 5148 APC when the realm fell to the Limit Princes and was briefly under the hated Limit Protectorate.
After the Dark Domain Frenzy of 3596 APC, the Hylacon Gates were weakened in ways that were not initially suspected. This allowed for a number of subversive invasions into the human continents from the Dark Domains, which had already begun in stealthy fashion during the time of the Second Popular Ascendancy but which accelerated after its fall. The Age of Shadows is characterised, in large part, by the arrival of sinister supernatural agencies and forces which sought to subvert civil society and find further ways to undermine the protection offered by the remaining barriers protecting the world from the Dark Domains. Their aim was to finally break the Hylacon Gates fully open so that a second invasion to rival the one that destroyed the Old Pale Empire after the Planar Conformation could be launched.
The chief instrument in the plans of the Ancient and Glorious for their liberation was the cult known as the Justice of the Shadows. Corrupted by a Shadow Sucker known as the Envoy, the membership of the cult expanded over the years until it was able to openly claim territory and aggressively expand in the south west of Tinturbean. In addition to that dread cult, there were other kinds of incursion, which included Noctipedes and the perhaps even more dangerous Dark Fakes which used mirror substitution to replace key individuals with a duplicate doppelganger. This technique had first been seen in the early years after the Planar Conformation. It's reappearance was a sign that the Hylacon Gates were no longer as strong as they needed to be.
In 5146 APC the Holy Battle of Oroth, successfully prevented the Justice of the Shadows from launching an expedition to destroy the Hylacon Gates and only three years later the arrival of Prince Rygarde brought an end to the age with the imposition of the Limit Protectorate.