Be dead and gone
Definition 1 of 2
Pro Tip 1/3Historical Reference
Use this phrase to indicate something has been completely gone from history, not just recently disappeared. 
The ways of the old empire are dead and gone, studied only by historians now.
Pro Tip 2/3Absolute End
Emphasize the completeness of an event's conclusion; it's not coming back. 
The old traditions are dead and gone, with modern technology taking their place.
Pro Tip 3/3Emotional Emphasis
Implies a strong emotional acknowledgement of something lost, often with a regretful tone. 
Her childhood innocence is dead and gone after all she's experienced.