The Seeding

Technological achievement

After the 200 year construction of the Rings, The creation and transportation of the galaxies races to the Ark were put underway. Each creature was transported with several thousands of it's kind to specific points on the Ringworlds and released. While the races weren't mindwiped or made to forget the experience, the creation and true origin of the Ringworlds has been forgotten and modified to be unrecognizable over the past millennia.