The positions of the equinoxes move westward along the ecliptic compared to the fixed stars on the celestial sphere.
These sites show a cultural continuity with the Vedic literature from the early Harrapan civilization up to the present day India.• The significance of establishing this date for the drying up of the Sarasvati River is, that it pushes the date for the composition of the Rig Veda back to approximately 3,000 B. E., as enunciated by the Vedic tradition itself.• The late dating of the Vedic literatures by indologists is based on speculated dates of 1,500 B. This piece of pottery from the lowest level of Harappan excavations with pre-harappan writing is deciphered as ila vartate vara, referring to the sacred land bounded by the Sarasvati River, described in the Rig Veda.
Often times, scholars use the astronomical signs mentioned in our ancient texts to date those texts.
The problem with this is that they do not provide definitive dates in themselves, but provide dates with repetitious cycles unless additional information is taken into account.
The one in March 20 is considered the spring equinox and the September equinox is the vernal equinox.
The precession of the equinoxes refers to the precession of Earth's axis of rotation with respect to inertial space.