In [[chronology]], an epoch is an event from which a [[calendar]] numbers its years. The most common epochs used in ancient societies were the accessions-to-the-throne of particular kings; hence a scribe might mark a date as "in such-a-year of the reign of such-a-king." The [[Rome|Roman]] Republic used as its epoch the year of the founding of Rome itself; hence the ''ab urbe condita'' date, but later abandoned that system and simply named each succeeding year after the [[consul|consuls]] who governed the state in that year. For example, the year we number as 70 BC was called ''annum consulatis Gnaei Pompeii Magni et Marci Licinii Crassi'', because the Roman statesmen Pompey and Crassus were consuls in that year. With the coming of the Empire under [[Augustus]], Romans marked their years as "in such-a-year of the Principate of such-an-Emperor." The First Republic of [[France]] briefly used as an epoch an arbitrary year in which they instituted the [[Joseph Lagrange]] [[French Republican Calendar]]. Finally, [[Islam]] uses as its epoch the [[Hegira]], or the flight of [[Muhammad]] from [[Mecca]] to [[Medina]]. This occured in 632 AD. | In [[chronology]], an epoch is an event from which a [[calendar]] numbers its years. The most common epochs used in ancient societies were the accessions-to-the-throne of particular kings; hence a scribe might mark a date as "in such-a-year of the reign of such-a-king." The [[Rome|Roman]] Republic used as its epoch the year of the founding of Rome itself; hence the ''ab urbe condita'' date, but later abandoned that system and simply named each succeeding year after the [[consul|consuls]] who governed the state in that year. For example, the year we number as 70 BC was called ''annum consulatis Gnaei Pompeii Magni et Marci Licinii Crassi'', because the Roman statesmen Pompey and Crassus were consuls in that year. With the coming of the Empire under [[Augustus]], Romans marked their years as "in such-a-year of the Principate of such-an-Emperor." The First Republic of [[France]] briefly used as an epoch an arbitrary year in which they instituted the [[Joseph Lagrange]] [[French Republican Calendar]]. Finally, [[Islam]] uses as its epoch the [[Hegira]], or the flight of [[Muhammad]] from [[Mecca]] to [[Medina]]. This occured in 632 AD. |