Andromedans

The Andromedans were a subgroup of Athos that had lived within the Andromeda galaxy. During the period of Athetian intergalactic expansion, the massive civic fleets that travelled to Andromeda underwent the effects of Psionic Incursion. Since Andromeda was a much older galaxy, there was much more  Yì Radiation  within it. This excess of  Yì Radiation  heightened the minds of the passengers of these large civic fleets. This strengthening of the mind, along with the increased distance from Arkitechtos, thus weakening its ability to transmit its suggestive field, is what allowed the Andromedans to break free from the rest of their empire. Of course, this process took several hundred thousand years, as Psionic Incursion on such a large scale is a slow process, but once it was complete, the Andromedans were able to realize what was going on with their people, and they decided to break away.