Throughout the Ages of the Alliance, a profound belief in reincarnation persisted. Though usually tied to various religious organizations, it was no uncommon to see even agnostics and unbelievers fervently argue in favor of the notion. Numerous studies took place over the years, some with limited success.
The Foundation, however, well known for definitively proving or disproving various rumors, discovered the explanation through historical texts.
The ideology began during the Mage Wars, when it was actually possible, through magical means, to re-incarnate into a new body, taking all of the knowledge and power one had gained in their previous life. The practice was known to be common during the Early Dynastic Period though was very likely perfected sometime during the First Chaotic Period
The Mehi Codex
The oldest contemporary account of a magically reincarnated individual dates from 2377 B.G.A., and is part of a collection of ancient documents known as the Mehi Codex. The Codex is mostly an historical account of various events around the era, so it is difficult to say when exactly the event in question occurred. The codex itself has been conclusively dated. In this excerpt:
She sits astride a horse, looking equal parts comical and adorable.
A child, to be sure, perhaps not even half a decade in years
Her long hair, tied in a traditional topknot, is an uncharacteristic shade
Her tiny, lithe body is swaddled in shimmering armor,
A cacophony of medals draped across her chest
And yet this tiny, helpless, innocent girl-child...
Is the living incarnation of Chester Rumbarahl
Feared warchief of the Seven Plains, Conquerer of Tel-Ebec
She sits astrid her horse, leading entire armies into battle, commanding magics
This small being, barely advanced in years enough to speak
In life, Rumbarahl saw ninety-seven summers, and in them mastered both spell and sword
His death, though long anticipated, saw little concern
He had time to plan, to lay the foundations for his return
And so, when his first life ended, he began his second, unfettered
Returned to youth and vigor, he resumed his old role and titles
The Diary of Skolla Shawni
Not an actual diary, but a treatise written about his life and experiences, the Diary of Skolla Shawni provides one of the most chilling first-hand accounts of a reincarnated individual, from the perspective of someone who knew the person during what he estimated to be its "sixth or seventh" lifetime. The author, Skolla Shawni, lived an unremarkable life in the mid-to-late Sixth Age, but gained much notoriety when his treatise was published. His thorough knowledge of history, gleaned only to understand the story, was later used in updating The Accepted Histories.
Skolla Shawni's Reincarnation Studies
Through meticulous research, Skolla believed he was able to identify thousands of individuals who he believed were reincarnated, and even isolated several distinct "reincarnation lines", or groups of reincarnates whom he felt were the same person. His primary goal was to identify as many lives as possible of his best friend, Zephanie Gahliardi, who was a reincarnated Marcon sorcerer, but he discovered others as well.
Skolla's research also gave rise to an interesting theory. Most of the reincarnation lines he identified began life as men, usually Marconians, but as the eons passed, they were most often reborn as women. The known lives of Chester Rumbarahl would tend to back up his claim, but not enough confirmed reincarnations have been recorded to prove it.
Another historian offered a dissenting opinion: the majority of Skolla's identified reincarnates were made decades or centuries after their deaths, chiefly through careful study of personal diaries. Since women are more likely to keep diaries and to write down the sort of thoughts that would prove their status, it logically makes sense that more of them would be identified.
Various "instruction manuals" have surfaced over the years, indicating when is required to create the permanent ritual site and make reincarnation possible.