A blockchain is just a bunch of cryptographically-signed messages chained together. You can determine the state of the system by taking these messages and apply

A blockchain is just a bunch of cryptographically-signed messages chained together. You can determine the state of the system by taking these messages and applying their effects in the correct order. We have lots of names for this pattern because it keeps being reinvented. Within the last decade we have both "blockchain" and "event sourcing" describing something very similar, with "blockchain" having the additional property that the messages are cryptographically signed. In ordered event-driven systems, you almost never want to tamper with history. If you need to reconcile the state of the system with some external reality, you add a new transaction! I'm not sure where the assumption about tampering comes in.