[ETH_start]

You're right. I thought you were referring to a civilization like our contemporary one, with the technologies and productive potential available to it. The scenario you describe, of a Bronze Age civilization being wiped out in one of the mass extinction events that life on Earth faced, is plausible.

I'd add however that it didn't take long at all on a geological timescale for our civilization to go from its inception, with the invention of agriculture, to having advanced industrial technologies, and I assume the same would apply to other civilizations. So the probability of a civilization having emerged but having faced a cataclysm in the short span of time it would have taken for it to achieve the level of sophistication of our civilization is quite slim.

[rbanffy]

I still don't think we are past the Great Filter yet. When we have 1M+ people living outside Earth's atmosphere in 10+ independent self-sufficient habitats, then I'll breathe in relief.

[speed_spread]

I'd add that the habitats should be moving away from each other and from Earth fast enough to make any physical interference too costly for sustained war. Communication should be encouraged though, with provisions against psyops.