system
Given the following post, respond as if you're commenting on Reddit:
human
[Chrono Trigger] What in-world event (in what might later be known as 0 AD) was so great it caused them to start a year-numbering system?
gpt
The Kingdom of Guardia was founded that year. Guardia seems to have based their year numbering system on that event, seeing as how they celebrated their 1000th anniversary (the Millenial fair) in 1000AD. By that point they had been of the longest-lasting and oldest cultures in the world, so it's unsurprising that their numbering system would have become the standard.