Imprisonment of the Necromancers
In A.Y. 3411, Pendragon Lal Soratami openly condemmed Necromancy, regardless of a given temple's ideology. Nearly all Grey Temple necromancers had been killed by the Necromanic Wars, and the few that survived were mostly in prisons for war crimes.
This, however, was seen by Soratami as insufficient to atone for the wars. At his command, armies under the direct control of the Slayer Dragons surrounded and laid seige to all Necromancer Temples in the known worlds.
Destruction and Dismantlement
At this time, there were no more established Grey Temples, and the Green Temples lacked central leadership.
As the temples surrendered, Soratami ordered their occupants put to death and the bodies burned (in Necromancy, this is the ultimate sacrilege). The contents of these temples were taken to Arindell to be stored in caches south-east of the city. Within a year, nearly all Necromantic temples in Alliance territory had been destroyed.
Temples in joint space were a little luckier, as at first they enjoyed some protection by the Gudersnipe Foundation. However, within the territory directly controlled by the Alliance and Gudersnipe, only the GS Towns really fell under the direct jurisdiction of the Foundation. For the first time in Alliance history, a Pendragon excercised the true control the Alliance had over joint space. Gudersnipe troops withdrew to avoid another war, and the last Green Temple was torn down and demolished by A.Y. 3425.
Last Bastion of Necromancy
During the fourteen years spent dismantling the temples and executing the necromancers, a few were spared. These were mostly children and young adults, born after the war ended. They were brought to Arindell to establish a new temple in the shadow of Stormwind Keep.
South-east of City Arindell, was a collection of buildings that contained caches of necromancer equipment looted from the other temples, along with records going back to the early Mage Wars. This area was fenced off and patrolled by guards, and the remaining Necromancers allowed to establish a temple inside.
This would become the last Necromancy Temple in all of the known worlds.
For 3,485 years and two complete Ages, all surviving Necromancers lived in a single temple in Arindell. Though population control was very strict, the place was still over-crowded and conditions were inhuman.
Jusenkyou's act was considered by many to require more power than the Pendragon could rightfully wield at that time. In fact, it was Pendragon Soratami's abuse of power in virtually annihilating the Necromancers that had led to the vast reduction in the Pendragon's power.
A mass exodus occurred at the temple in Arindell, as thousands of Necromancers left home to establish new temples elsewhere. The temple in Arindell was nearly abandoned, but would quickly be repopulated over the next few decades as its remaining inhabitants enjoyed return to the Necromanic tradition of large families.
Roughly ten years after Pendragon Jusenkyou freed the Necromancers, an Alliance committee finally ruled that Pendragon Soratami did not have the power to imprison the Necromancers in the first place. And while by that logic, Pendragon Jusenkyou also lacked the power to free them, they had never been legally imprisoned. For the 3,485 years the Necromancers had been in Arindell, they had been under the control of the city's civil defense force, which reported directly to the Slayer Dragons. While considered a part of the Alliance's military, this group was not under the control of any member world, and hence the containment of the Necromancers had been carried out by order of the Slayer Dragons; an order given over three thousand years earlier by a Pendragon considered a power-mad dictator by modern standards.
No Alliance law was ever placed on the books restricting the Necromancers' freedom. And while one might have been passed, dozens of new temples were already firmly established by the time this was determined.
Hence, the Necromancers remain free.