I recently realized that the stellarium desktop software has a bug when trying to calculate the location of the vernal equinox going back further than around 3000 BC or so; due to this bug I kept getting incorrect locations of the vernal equinox when I was trying to determine the time periods of various astrological ages.

The reason for the bug seems to be that the software continues using a gregorian calendar for very old dates instead of switching to a julian calendar. The way to resolve the issue is to take whatever ancient date you want to use and convert it from a gregorian to julian date first, afterwards you can take the new julian date, put it into stellarium and youll get the correct location of the vernal equinox. hope this helps!