Which period saw numerous short-lived 'barracks emperors' raised by the army? (235-284 AD)

Crisis of the Third Century is correct because from 235–284 AD the Roman Empire was rocked by rapid turnover of “barracks emperors”—generals proclaimed by their legions and often killed within months. This military anarchy, sparked after Severus Alexander’s assassination, brought civil wars, invasions by Goths and Persians, economic collapse, and rampant coinage debasement, until Diocletian restored stability in 284. To remember it, think “Third = Three-way split”: during this crisis the Empire fractured into the Gallic Empire in the west, the Palmyrene Empire in the east, and the central Roman core. By contrast, the Pax Romana was a long peace, and the Year of the Four Emperors (69 AD) was brief. The Third-Century crisis was a decades-long storm of soldier-emperors.