If you're asking the question I think you're asking, the following links should serve. If not, could you please clarify further what you're looking into, for the guidance of other potential answerers?

The Christian BC/AD calendar is just one amongst many possible systems of year counting. Various other alternative calendars exist, as we can see from the appropriate section of the FAQ, Other Dating Systems under Calendars, if your browser doesn't automatically take you there.

Indeed, BC/AD is simply a regnal calendar that refuses to change eras like normal regnal calendars. Multiple other calendar systems remain in use today. Japan still uses a regnal calendar for official purposes.

Posted on this day, Sunday 22 August; Quintidi 5 Fructidor, An CCXXIX; 31 Mordad of 1400 Solar Hijri; Reiwa 3; 7529 Anno Mundi; the fourth year of the 699th Olympiad; the fifth year of Rodrigo Duterte being President.