Humans have used calendars since eternity. All most every grown up human being uses the calendar everyday. Each civilization had their own calendar which perished with it.
The most widely used is the GREGORIAN calendar or the ENGLISH CALENDAR which is just 2020+ years old
What if there’s a calendar that’s much more ADVANCED & SUPERIOR than any calendar you have EVER COME ACROSS. Take a look at this video to know the The MYSTERY of the HINDU CALENDAR. Secret of the SANKALPA Mantras and the age of the UNIVERSE.