To the east Everast transitions from verdant coasts and sky-scraping mountains into the deep thresh of grasslands broken up occasionally by sprawling forests and the occasional lake. For Aevum prior it was considered a barren waste, untouched by the Knowing
However during the years predating the Infernal Conflict when enslavement of humans was still common, word began to spread of a small resistance to the east. Over the span of several years groups of humans fled to the east, following the coast and looking for "A boulder as large as a small hill, gleaming blue in the evening sun."
Trial followed these folk; death was common and expected but they forged east all the same. For those persisted after months of travel they found the proverbial blue boulder, what is now known as Salvation Rock in the city of Stonescoast, Dij Sune.
Over the years these numbers would grow, and as word spread, the small outpost would be known as Stonescoast, "the first city for the free human." Indeed no record shows a human-exclusive settlement existed since before the Ashcurse. The decades that followed contained explosive growth. Like a match to a bonfire resistances arose over the lands to the west, encouraging the First to rage against their shackles.
By the month these outpost villages were increasing by the hundreds as humanity found more and more ways to break free. In less than a decade culture shifted. New homesteads cropped up periodically as families of humans learned to farm. By the end of the fourth decade these lands became collectively known as "The Pridelands," the first thing in Aevum that humans felt they could be proud of.
Conflict developed as handlers and slavers began to forge the eastern lands. Bands of marauders and slavers hired by the elven lords to the west pillaged homestead and frontier town alike, recapturing the humans and returning them. Those that were successfully returned were treated more poorly than before. It was from among those newly enslaved that the tieflings were born.
During this period of strife and desperation there were some that believed that there would be no end to the pain that the elves caused. These hopeless few reached out to the infernal powers below, making dark pacts with devils for the power to defeat their foes. Some even say that the Lamia were invoked, and that the blood of the Mutes themselves still flows through tiefling blood today.
True or no, the actions of the invokers triggered the era of strife known as the Infernal Conflict as these empowered tear and tia pushed back. Wielding unknowable power in their veins the tieflings forged against the elven cities with guerrilla tactic and force. So great were the casualties of these terrorists that they threatened to wipe out the elves whole. In desperation the elven lords called for a ceasefire.
The elves called for an assembly of the sentient manifest. Emissaries from the kingdoms of gnomes, dwarves, dragonborn, and for the first time humans, all came to the elven city of Stratosmac. Over the next weeks deliberation on a solution was considered, finally resolving on the 17th of Viirlil, 3,018 Aevum Quartus. The universal rules of engagement decided on are now known as the Stratosmachta Accords.
It was within these accords that humans were recognized, for the first time, as a sentient and free race and were welcomed into the manifest. The tieflings were allowed to persist so long as they no longer attacked the elven lands, and in return the elves would not pursue capture of humanity.
Thus the Pridelands to the east were formed.