The High Antarctic Empire was an Ancient Terran faction that existed during the 98,000's BCE. The HAE was theorized in 2287 with the discovery of the "Kaiser Stone" and dozens of artifacts too advanced even for contemporary Terran technology, initially it was assumed to be leftovers from the well known Psion Imperium, but wasn't proven. In 2366 more artifacts and even an a buried skyscraper miles below ground was discovered and the "Ancient Terran Empire" was theorized once more.
With the Loreko's attack on Earth in 2511, the Arc Wave Amplifier was discovered in Antarctica intact, only 2000 feet below the ice near the south pole, the insignia of the creators faction was found as well, and inside hundreds of skeletal remains of ancient humans were discovered thus proving that the "High Antarctic Empire" was indeed real.
Subsequent discoveries on Mayana and Frontier in 2529 and 2593 respectively revealed that they were a powerful space empire, likely allied with the ancient Psion Empire. How they were destroyed is largely unknown but it's assumed that when the first Ravagers arrived at a similar date they had obliterated most of humanity and any other empire nearby, luckily the Son's of Belaren had defeated the relatively small Ravager force, but the HAE was destroyed and humanity was forced to start over.