Comment by betwixthewires

It doesn't have to be a blockchain. All these people selling "blockchain" are selling hype, the only reason you need a blockchain is if you're in an adversarial, permissionless environment and need consensus on state, and possibly need a record of historical state.

In a private system, you just need consensus among participants, potentially in an adversarial environment, but decidedly not a permissionless environment. As long as state can be kept, depending on the constraints of the system any sort of consensus and canonical state keeping mechanism would work. Could be a blockchain or something resembling one, could just be a document and it's hash kept by all participants and updated when the participants agree to a change. How complex you make consensus in a permissioned system depends on the goals and constraints of the system.