Taken from the Author's introduction to Paying the Price of Humanity's Pride by Taan No'Lop - avid historian and warlord.

A thousand years ago the greatest engineering marvel the Galaxy had ever seen was made and instantly abandoned. Without explanation the Humans, architects of the project and greatest power in galactic history, shut up shop and created a quarantine zone 10,000 light years deep around the vast artefact they had created. Whole space-faring Cultures, some considered to be great in and of themselves, were moved outside the quarantine zone and compensated in what ways possible for the loss of their homeworlds.

Then, with grim warnings for anyone daring to cross the quarantine border, the Humans simply up and vanished. Some say they transcended to another plane of existence, some say they moved to the neighbouring Andromeda galaxy to start over and yet others claim they committed suicide en masse to erase their shame at the Grand Project which had so obviously failed. Either way, they were never heard of again and their name and fame entered legend.

The decades passed and then the centuries and the warnings became less important than the need to explore, expand, annex and escape. Cultures began the journey across the stars into the Quarantine Zone finding pristine worlds that had been all but stripped of any former signs of civilisation. A hundred species settled again on a thousand worlds - starting over or expanding their influence. But there was something curious about these worlds in that none of the Cultures that settled on them ever seemed to advance beyond a certain level of development. Technology seemed to stagnate at a level reasonably equivalent to the middle of the 20th century on Old Earth. There was no rational explanation for it, but projects never seemed to advance, more advanced technology developed elsewhere seemed to fail with alarming regularity and even art and religion seemed to stagnate along with everything else. Due to the difficulties of getting to these worlds they became isolated again, and many fell back into ruin and lawlessness. After 500 years these worlds in the Quarantine Zone were once again isolated, and this time the warning of the Humans was remembered and obeyed. The worlds in the Zone were left to their own devices, outside a few tentative explorations or invasions that all came to ruin, and the worlds prospered or failed on their own for the next half a millennia.