Covering the reigns of the emperors Constantius, Julian, Jovianus, Valentinian, and Valens. According to Wikipedia: " Ammianus Marcellinus (325/330âafter 391) was a fourth-century Roman historian. He wrote the penultimate major historical account surviving from Antiquity (the last was written by Procopius). His work chronicled in Latin the history of Rome from 96 to 378, although only the sections covering the period 353â378 are extant."