The rise and fall of fortunes or power; vicissitudes — the alternating periods of prosperity and decline.
王朝の盛衰は長い歴史の中で何度も繰り返された。
The rise and fall of dynasties were repeated many times throughout long history.
彼は業界の盛衰を目の当たりにして慎重になった。
Having witnessed the industry's ups and downs, he became cautious.