If you will recall a place used over a century ago called Botany Bay. This was off shore to Australia and in it's time period, convicted felons were literally dropped off there by ship and just forgotten about. If they survived, that was fine. If they died, that was fine also.
Botany Bay was a penal colony. The French also had one called Devil's Island around that same time period.
Obviously, this is completely different from a prison, where the law demands that inmates are watched over, looked at, medically cared for and protected until their release.