Duality of Metaphysics
It might be hard to imagine a time before the various races of Tarien understood the dichotomy of the soul and the body. Before Andra Moeynshiem's seminal work, however that is exactly how most saw existence. A person was merely their body and, upon its death, they simply ceased. Even after Merdenkali Shal'Ratzen summoned the children of Nosferian to his aid, no one thought of them as former mortal souls; they were simply powerful beings of a different nature, like a giant or dragon.
Moeynshiem's work changed everything. Ostensibly a philosophical work, she uses reductive logic to arrive at the conclusion that a person's body is merely a vessel for their essence and that vessel is merely temporary. Citing cases of possession, near death experiences, and even folklore where a child knows stories that only one of its ancestors might know, she makes her arguments convincingly. While she did not delve into the theories about what might happen to that essence, which she termed their true "Soul" (after the Soulmeliti word for "trueness to oneself", the ramifications of her work resonated throughout religious circles.
Worshipers, who had traditionally worshiped and sought out the blessings of various deities for practical matters - such as healing a sick family member or luck in a coming venture - began to consider their eternal lives as part of religious considerations. Various acts might curry favor with a deity and allow one a comfortable afterlife, be it basking in the light of Anderi or returning as a mighty tiger in the Shar’iish’tic tradition. Religious leaders found that these concerns drove their flocks even more than mundane ones and pushed the ideas forward. People even began to suffer hardships on Tarien with hopes of improving their eternal stature. Powerful priests even went a step further and experimented with prayers designed to reunite departed souls with their bodies, performing the first miracles of resurrection, a practice that lead has since ceased with the Unidirectional Migration of Souls.