The Sathar invasion of the region started 1000 years ago on Volturnus. The Sathar hit that world hard, out of a severe fear of the Eorna and their psionic power. The Sathar learned fairly quickly that their species was particularly vulnerable to the type of psionics the Eorna practiced. They developed armor to protect them but it only proved mildly effective.
The war waged for years, delaying any further invasion into the region. The Sathars war with the Eorna took more resources than they even planned on. They had to resort to genetically engineered soldiers (Ul-Mor, and Karabanda), engineered by another slave race, the Edestekai, because their own inherent vulnerability to the Eorna psionics. This turned the tide fairly quickly. Controlled by a psionic beacon, these soldiers proved to be most effective against the Eorna psi-warriors and psi-casters.
The Psi-Knights of Tazelo Ish (translated Hidden Thunder) were an order of Psi-casters of unprecedented power. A secret order that were only spoken in myth and legend, likened conspiratorially as an illuminati-like group, they arose to defend the race late in the war. They were rumored to be behind all major political and social events in Eorna society. They were rumored to have power enough to effect the planet’s environment. Unfortunately, their efforts to save their world were too late.
They watched as their civilization crumble. The surviving population were already on escape ships or already on the orbiting space stations. Their ruling council finally decided they had to do something. As the destructive city-destroying bombs proceeded to level city by city, the Psi-Knights called forth power like they have never called before. Other races, still bound to their planet, have legends and myths of this event as their astronomers saw it occur. Through the power they summoned, the Xagyg Nebula formed.
In their attempt most of the Psi-Knights died. Only one survived (The Eorna in the adventure). He and a handful of acolytes retreated into the ruins of the capitol city. The Sathars invasion was halted by the massive nebula and it took them another 1000 years to finally muster enough resources and navigate the nebula to invade beyond.
ENIGMA
(idea) In truth, it was the Paladins fault that the Sathar found Volturnus. In an attempt to grow their power, the contacted beyond – the masters of the Sathar – the Externals (Star*Drive).