There are a bunch of crypto currencies now, but back when they were first starting out the main feature was that cryptography could be used to establish and maintain a distributed ledger of ownership amongst the participants of the currency. And to this end, the first implementation of a crypto currency was with the giant Rai Stones of the Yap Islanders.
The Yap islanders, who lived in present day Micronesia, would make circular stones--some eight feet high--and use them for trade in important transactions. Since moving giant rocks around isn't the easiest, the yapese instead would just leave them where they were, and keep an oral ledger of who owned what rock. The system was cryptographically secure by the language of the yapese, and the consensus that they had as a community.
Of course the yapese had the same problem that crypto does, which is that when the British show up, since you're not part of their marketplace, they'll just take all your fucking rocks.
If you feel that the secp256k1 elliptical curve somehow protects you from governmental forfeiture, perhaps read a bit on the yapese, and like almost every other group of people who ever had other people invade them.
Which leads me to Planet Nine's Experiments With Money.