It was once in use throughout much of East Asia: https://en.wikipedia.org/wiki/East_Asian_age_reckoning https://en.wikipedia.org/wiki/East_Asian_age_reckoning

It was once in use throughout much of East Asia: https://en.wikipedia.org/wiki/East_Asian_age_reckoning https://en.wikipedia.org/wiki/East_Asian_age_reckoning As an American, I remember first encountering it in a footnote to an English translation of the Tale of Genji.