[chema]

Absolutely. Years ago I made what is essentially a Unix time / Maya Long Count converter and I was very pleased with how similar they were in concept (i.e. counting seconds or days from a particular epoch) with the only major difference being the base 10 vs base 20.

https://github.com/chema/long-count

[Someone]

> I was very pleased with how similar they were in concept (i.e. counting seconds or days from a particular epoch)

I don’t think there are many alternatives. Counting backwards would either mean diving into negative numbers or postponing that by starting at an arbitrary high number.

“In the x-th year of ruler Y” plus a knowledge of the succession of rulers is awkward for recording over centuries. I expect that has been used almost everywhere before history (in the meaning of ‘after prehistory’ https://en.m.wikipedia.org/wiki/Prehistory) began, but as far as I know, where written records exist, countries that used it such as Japan also had another system (https://en.wikipedia.org/wiki/Japanese_calendar)

[fanf2]

The reason the Julian day number is important is because Joseph Justus Scaliger went to enormous effort to create a consistent chronology of ancient and mediaeval history from records that mostly used regnal years. Sometimes they might use other calendars, or refer to the 19 year metonic cycle (determining the date of easter) or the day of the week (a 28 year cycle) or the year in the indiction cycle (a 15 year tax period in the eastern roman / byzantine empire). His chronology covered several non-european cultures as well as graeco-roman history. It is neat that astronomers are using a modernized version of his dating system, so ancient records can be more easily matched to modern observations.

[chema]

Most calendars still use internal cycles. These two calendars are more comparable to the astronomical Julian Day.