The period when something or someone was most flourishing; largely synonymous with 'heyday'.
その作家の全盛時代には新刊が次々と出た。
In the writer's heyday, new books were published one after another.
この町は江戸時代に全盛時代を迎えた。
This town reached its heyday during the Edo period.
全盛時代の名残を探すのは興味深い。
It's interesting to look for traces of the heyday.