Premise: Year 493 BC was a year of the pre-Julian Roman calendar. At the time, it was known as the Year of the Consulship of Auruncus and Viscellinus (or, less frequently, year 261 "Ab urbe condita"). The denomination 493 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.
Hypothesis: Year 493 BC was before the birth of Christ.