When someone decides to change the way that they keep track of time, the new calendar typically starts at 1, as in “the first year of this new era”. It’s not that there was no existing year before that, just that it doesn’t make sense to start as zero.
It’s not like the Gregorian calendar that we use now existed in -1 and then rolled over to 0 and then 1. They just started the new one at 1, and for a period of time, there was surely some overlap in people using both calendars, until one was phased out entirely.
They started the new one around 525 and just backed dated everything before then. Year 1 was never observed in the modern calendar system. Most other calendars started with a year 1 on the day the king decreed it so (often the day he became king)
When someone decides to change the way that they keep track of time, the new calendar typically starts at 1, as in “the first year of this new era”. It’s not that there was no existing year before that, just that it doesn’t make sense to start as zero.
It’s not like the Gregorian calendar that we use now existed in -1 and then rolled over to 0 and then 1. They just started the new one at 1, and for a period of time, there was surely some overlap in people using both calendars, until one was phased out entirely.
The year 1AD wasn’t called 1AD in 1AD. The system was invented hundreds of years later.
Korea kinda takes this to the extreme with birthdays.
They started the new one around 525 and just backed dated everything before then. Year 1 was never observed in the modern calendar system. Most other calendars started with a year 1 on the day the king decreed it so (often the day he became king)