Before Blockchains, most people who cared about cryptography were well aware of Merkle Trees. They date back to 1979. Yes, there's also the proof-of-work part.

Before Blockchains, most people who cared about cryptography were well aware of Merkle Trees. They date back to 1979. Yes, there's also the proof-of-work part. We had that in 1999 with Hashcash. The only thing bitcoin brought to the table was moving proof-of-work from a trusted hardware module to a P2P network.