There was very little known about the Querat, for few actual sites were investigated and not many of their artifacts survived. Archaeological evidence for them was largely second-hand. However, it was known that they were a multi-world society in the Coreward end of the Galaxy during the late Second Interregnum when they began expanding. Eventually, they came quite close to the Federation homeworlds, but they never reached Rigel nor into the Orion Arm.
Their rise ended the Second Interregnum of the Emergent Era, while their decline began the Third Interregnum, though this date was not precisely known. (FASA RPG - The Orions module: Book of Common Knowledge)