The invasion lasted for decades, but then abruptly ended in about 2820. To protect their homelands, some brave Hai, who would later become the Unfettered, rose up to resist the invaders. Several centuries ago, the Hai were invaded by an alien species, the Korath. They pulled out of what was to become human space and the ruined northern territories. About when those wars ended, the Hai decided that they would be better off with a small collection of systems than with a large empire. They had a period of civil wars stretching 5,000 years, from 92,000 B.C.E to 87,000 B.C.E.
We know that the Hai empire expanded up to what is now Wanderer space and all the way out to the Deep. The Hai developed spaceflight in about 117,000 B.C.E and they reached the peak of their empire at about 97,000 B.C.E.