ANd then we would of by now found at least a few bits and pieces of hardware laying around !
I believe the ancients didn't start recording history till much, much later than cave-drawing times, and I don't think there's any chance they would last anyway (e.g. the Library of Alexandria)..
As for the hardware.. Assuming they were made of metal (if they existed), they would disintergrate to nothing much quicker than you think.. Its believed even entire cities like L.A. or New York would be gone, without a trace, within a mere few millennia. Metals oxidize rapidly.