turbulent times; war-torn era
Refers to a period of constant warfare and social upheaval, often specifically the Sengoku period in Japanese history.
Stories of warlords who survived the turbulent war period remain popular today.
戦国時代 is the standard historical term for the Sengoku period, while 戦国乱世 emphasizes the chaos and upheaval of that era.
Compound of 戦国 (warring states) and 乱世 (turbulent world). The exact historical derivation is uncertain, but the term is conventionally associated with the Sengoku period.