Countries with alternative calendar systems?

[accountingwitch]

To prepare for a story, I'm looking for countries/eras/kingdoms that have alternative calendars. For example, North Korea's is based on the birthdate of its first leader and Taiwan's on the date it was founded. I'm looking for modern examples like these, but past ones would be good as well, preferably ones that lasted longer than one person's reign.

Google-fu has failed me, since I could only think of "alternative" + "calendar" (religious date calendars - not what I'm looking for) + "north korea" + "taiwan" (political documents).

I'm not looking for religious ones. I'm more focused on countries with calendars based on historical events or famous people.