390 BC was a year of the pre-Julian Roman calendar. At the time, it was known as the Year of the Tribunate of Ambustus, Longus, Ambustus, Fidenas, Ambustus and Cornelius (or, less frequently, year 364 Ab urbe condita). The denomination 390 BC for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.