>>13014460There have been theories posed suggesting stuff like this, such as the Silurian hypothesis. Essentially objects would be long decayed if there was a civilization very long ago (think Permian). There could be indirect evidence such as the presence of nuclear materials, plastics, evidence of mining etc. If they never reached industrial then we would not be able to detect them.
The most certain sign of an industrial civilization would be if they left something on the Moon, since it could persist there for much longer than on Earth.
