The Exile
The Exile is an event where the Spirit Valley Tribes have been compelled to flee their homelands by the Spirit Wilds. The event has been highly disruptive to the culture of the tribes and saw many casualties, as well as the beginnings of new culture and religions to understand what had happened to them. Upon entering various established powers, the tribes' presence would lead to violence and discrimination frequently.
Pre-Exile Context
While the location of the original homeland of the tribes is now understood to be the southern banks of the Spawn Lake, outside contact with this area was fairly limited. As a result, we know very little of tribal culture prior to the Exile. "Codices of the Southern Tribes", an attempt to study the tribes by the Church of Fire, cites a "former Othii general" who describes their old way of life as such:
Our people thrived in the homeland we can never return to. The land was bountiful, and we lived in harmony with the trees. We took enough land for crops that we might feed our people, but we knew to leave enough for the trees such that we might hunt. Our warriors were mighty, and our people stood strong. There were many tribes back then - we sometimes warred, we made peace, we married. Nothing is the same.
The same general notes that, while his parents did live in the homeland, he was born during the Exile. In this account, he also states that spirit raids were a regular but minor issue, and that the regular attacks of the Wilds were "once in a generation ... every week, soon every night". We can discern here that there was a hostile relationship between the tribes and wild spirits from this, but one where the tribes were either superior or at least equal.
In the context of the Exile, the Tribes are often split into two groups: East, consisting of the Othii, Carnii, Kaerii, and the now-extinct Senerii; West, consisting of the Toshkii and Galethii. No other tribes are known at this moment.
We were not the only ones forced to flee. We never heard from our cousins to the west, as we were split forever by the spirit hordes. Some tribes elected to stay, whom we never heard from again.
It is clear from the Codex's account that this division did not seem to exist prior to the Exile, being more of a regional identity than a distinct ethnolinguistic group. Most accounts of the Exile seem to state that the Spirit Wilds began their attacks from inside the homeland, pushing outwards. As the sea contained the northern and southern perimeter, this forced tribes to move in one of two directions, East or West. This separation is likely what caused the split.