Though the term calls to mind cryptocurrencies, a crypto-civilization is actually a highly advanced society whose existence has been hidden or suppressed by the dominant culture or ruling power. Oftentimes, a conqueror will throw down the sacred images, statues, and symbols of the people(s) it has vanquished, as in the practice known as iconoclasm. The political and priestly classes of the conquered peoples may be imprisoned, exiled, eradicated, or given token positions of authority in the new regime, thus breaking the power centers of the subjugated peoples, and interrupting the transmission of accurate history across generations.
In such scenarios, it is common for historical revisionism to likewise occur. Events which were once taught and understood to be history are ridiculed, and relegated to the domain of myth and legend, before being forgotten about altogether. Supporting historical artifacts and evidence that are not destroyed outright may be re-contextualized by the dominant power to tell an entirely different tale than their true origins and use.
This process of occultation has been applied again and again throughout history since antiquity, and even back into prehistory in the case of the mysterious Quatrian civilization. In actual fact, the ancient Quatrian crypto-civilization massively predates all other canonically-accepted human and proto-human cultures by millions of years according to some sources.
Interestingly, the ancient Quatrian crypto-civilization did indeed have certain commonalities with contemporary cryptocurrencies. For one, the civilization was composed of a web of autonomous colonies that were politically decentralized, and globally distributed (thanks to their mastery of reed boats). Their government was a type of resilient poesiarchy composed of bards and minstrels of various types who traveled from place to place, transmitting their oral histories, tales and legends, along with techno-cultural knowledge. Applying this back to the metaphors of modern cryptocurrencies: if we think of a dominant culture’s history as a consensus system running on a blockchain, then the crypto-civilization’s history and timeline could be thought of as either a suppressed sidechain or else an unauthorized fork from consensus reality.