Wikipedia:WikiProject Microformats/dates
 | This page in a nutshell: Don't use templates that show dates in a special format for years before 1583 or after 9999 CE. |
Wikipedia's date templates don't handle dates in calendars other than the Gregorian calendar yet.
We don't say we stick to ISO 8601. However, ISO 8601 says people need to agree before using years before 1583 or after 9999. So, using templates for dates outside that range or in non-Gregorian calendars might confuse people.
Any editor that sees dates used like this, change them to regular text with no date template. If you're not sure how to do it, you can discuss it on the talk page for that topic.