What was the original basis for the sequence order of the twelve astrological signs?

Answer

The vernal equinox marking the start of spring

The twelve signs follow a fixed sequence established in antiquity, beginning with Aries at the vernal equinox, which historically marked the start of spring and the astrological year.

What was the original basis for the sequence order of the twelve astrological signs?
astronomyZodiacplanetsskycelestial objects