Both Uses

oblivion
in
Gone with the Wind
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I think that if it hadn't been for you, I'd have gone down into oblivion— like poor Cathleen Calvert and so many other people who once had great names, old names.†
Chpt 5.53 *

oblivion = a state of being completely gone from memory, existence, or awareness
The Gelerts and Hundons, evidently apprised of Bullock's departure before his resignation became public, left town abruptly, disappearing into that oblivion from which they had come.†
Chpt 5.58

Definitions:

(1) (oblivion)
state of complete loss—being totally forgotten, wiped out, or lost to awareness of what is going on
(2) (meaning too rare to warrant focus)