About a hundred years ago a hoard of wonderfully preserved, 2,500-year-old papyri were uncovered on Egypt’s Elephantine Island, in the Nile River in southern Egypt. These bills of divorce, commercial contracts and other legal documents were written in Aramaic, the language of Elephantine’s Jewish and Persian settlers (Egypt was conquered in 527–525 B.C. by the Persians, who employed Jews from Palestine as mercenaries to guard Egypt’s southern border).

These papyri often record events using both the Babylonian lunar calendar and the Egyptian non-lunar calendar. They thus provide a record of dates reaching back as far as the fifth century B.C. In the following text, for example, the date of the manumission of a female slave and her daughter is recorded in both calendars—which turns out to be June 12, 427 B.C., in the modern calendar:

“On the 20th of Siwan [according to the Babylonian calendar] that is the 7th day of Phamenoth [according to the Egyptian calendar], the year 38 of King Artaxerxes Zakkur [who ruled from 465/464–423 B.C.], a Jew of the fortress Elephantine, of the detachment of Arpakhu said to the woman Tamut (as she is called), his slave, who has on her right hand the marking ‘Of Meshullam,’ as follows: I have taken kindly thought of you in my lifetime, I hereby declare you released at my death and likewise declare released the daughter Yehoyishma (as she is called) whom you have borne to me.”