This is the 582nd most frequent Japanese word.
かつて
"かつて" means "once" or "formerly."
In this sentence, 'かつて' specifies a role or achievement from the past that isn't current anymore.
彼女はかつて名高いピアニストだった。
She was once a renowned pianist.
The use of 'かつて' here denotes that a significant historical event took place in this area long ago.
この地域はかつて戦争の中心地だった。
This area was once the center of a war.
Here, 'かつて' implies something that existed or was the case in the past but is no longer true.