Abstract
Ancient Indian eras are found in inscriptions, colophons of manuscripts, and referenced in literary and scientific texts and determining the duration of an era serves as an important tool in reconstructing Indian history. Eras can be counted in regnal years or as a continuous era. An era based on regnal years typically concludes at the end of a king's reign, whereas if a subsequent ruler uses these dates the era becomes continuous, and continuous eras can persist for centuries or even millennia. The two ancient Indian eras still in use today are the Vikrama era, which started in 57bce, and the Śaka era, which began in 78ce. Besides these two eras, there were many regnal and continuous eras that emerged in ancient India but did not persist to the present.