Construction of the Fey Gate was ordered by Alta Rapids after the disappearance of her husband. It was completed in 9,600 B.E. Prior to the gate's existence, the people settled in the northwest of the Broken Earth commonly encountered the fey. Their land is located further north, on the other side of the gate, but they were known to visit and create agreements and mischief.
The settlers and the fey got along relatively well for quite some time. For unknown reasons, around 9,555 B.E., more and more people seemed to fall under some sort of fey influence. They acted oddly and then would begin a pilgrimage into fey land. Once they passed that threshold, they weren't ever seen again. After Kin-Ail Rapids disappeared with a large portion of the royal guard, Queen Alta was left as the sole monarch of the Rapids family. She ordered the remainder of the guard to follow after and construct the gate to prevent people from wandering away from home. There was little fey interference with this, which was a surprise, but instances of people disappearing into fey land is no longer an issue.