431  Year 431 (CDXXXI) was a common year starting on Thursday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Bassus and Antiochus (or, less frequently, year 1184 "Ab urbe condita"). The denomination 431 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.