The Little Unmaking

The Second Unmaking was officially over when the last of the Demon Lords was slain and the Nine patched up the hole rent in the Barrier
When the Demon Lords were slain, their armies of minions didn't spontaneously combust. The remnants of the Demon Lords' hordes dispersed and rampaged across Scarterra and Scaraqua in a sporadic fashion. While the main rent in The Barrier "fixed", The Barrier was still weak for decades if not centuries, letting more demons sneak into the material plane.
The Little Unmaking is a term scholars use for the transition period between the end of the Second Unmaking and the start of the Third Age.
Humanity was young and not very numerous or well organized. The surviving mortals of the Second Age were not in great shape either. They had to build up their livelihoods from the ruins of the previous Age while dealing with frequent small scale demon attacks and very harsh winters.
On the plus side, the Nine were especially proactive sending spirits to aid mortals of all stripes.
Because it was a struggle just to survive, there wasn't much time to chronicle events. Written records for this era almost nonexistent. It's not even clear if this period lasted for one hundred years or one thousand years.
Legends of this era are vague. Even with the aid of scores of spirits of wisdom, humanity and the other mortals were fairly promotive and disorganized. Feudalism hadn't emerged yet and the various geographic corners of Scarterra had almost no contact with each other.
The various priesthoods of the Nine had to rebuild themselves practically from scratch. The priesthoods did not have inquisitorial bodies to root out Infernalists who were far more common in Scarterra than in feudal era that followed centuries later.
There were tiny pockets of settlements ruled by competing warlords surrounded by monster and demon infested wilderness
This era of Scarterra might qualify more as Sword and Sorcery than High Fantasy.