The fate of Galaxy Three's prediscovery civilization stands as a stark warning of what might have been, were it not for the profound wisdom of the Progenitors. Bereft of that wisdom, Galaxy Three's native civilization suffered the inevitable spiral of decline into disaster that awaits all who spurn the teachings of the progenitors. Galaxy Three has been exhaustively studied and this small branch can only briefly summarize the conclusions of those eons of study, but it is still a valuable object lesson. (See bibliography)
The Founders of Galaxy Three are of unknown origin. They definitely were not the Progenitors themselves, but appear to have been lesser beings of the same ilk. All the evidence is available in the Galactic Library's Archive, but the arguments are too complex to be summarized by this brief synopsis.
The Founders uplifted every suitable species in Galaxy Three, giving them Galactic-equivalent technology but evidently no traditions to instruct them in its responsible use. While the Progenitors had the foresight to conserve biospheres, the Founders simply stripped them of everything immediately useful, then built planet-wide cities filled with wonders, but devoid of wildlife.
In time, the Founders departed, their destination as obscure as their origins. Their clients followed the example of the Founders, occupying every habitable planet and severely degrading biospheres. This left no suitable species for the next generation of Galaxy Three's patrons to uplift, and without fresh clients the civilization of Galaxy Three had doomed itself. One way or another the patrons would pass on, and there would be no clients to inherit their legacy. All that remained was to see how Galaxy Three's Main Sequence culture would perish. Had any of Galaxy Three's patrons been able to achieve Retirement they would doubtless have been able to prevent the slide to disaster, but it is thought that none did. The records are not entirely clear, but there are few known cases of clientless races successfully Retiring. Why clientless races seldom retire is as mysterious as everything about the Retired, but it is suspected this is the reason for the interest the Eldest show in the youngest clients.
There had been wars in Galaxy Three soon after the Founder's departure, as the new patrons jockeyed for territory, but they had been softened by memories of the unity enjoyed under the Founders, and soon subsided into uneasy peace, a balance of power maintained by constant skirmishes. The ever increasing population pressure remained, and it was clear war would return, but the spark was unexpected.
One patron race, recognizing that there was something missing from their Galaxy, managed to create a cyborg race. The other patrons, fearing increased competition for resources, immediately launched all-out war. None of the allies trusted each other, and rightly so. No sooner had the cyborgs and there creators been exterminated than the allies turned on each other, each seeking sole dominion. Fleets of berserker Von Neumann machines were launched, programmed to destroy the enemy. They succeeded. A few planets survived, but without interstellar trade civilization collapsed, leaving only primitive cultures, devoid of space flight. Those were the lucky planets. Most planets were visited by several swarms of berserkers, which stripped them of all macrofauna in a Permian level extinction.
When the Progenitors eventually found Galaxy Three, there was no living trace of its native culture left, just millions of ruined worlds and a few simple tribes living in the ruins of their ancestor's glory.