Astrology

There was definitely a pre-yavana Indian astrology. It was just of a different nature from the jAtaka and hora astrology of yavana origin. The old astrology is found in the aushanasa adbhutAni and nakShatra parishiShTha-s of Atharvan tradition.

No planets are involved but it works mostly as omenology: e.g. when a planet goes close to rohiNI alpha Tauri they said the following could happen: lakes drying, rivers changing course, suffering to animals including humans, the saMrAT dying.
In a more cryptic account a disease, lasting 20 nights said to arise during planetary conjunctions.
A planet going close to the kR^ittikAH (Pleiades) is said bring death to goats, sheep and rats.

Different varNa-s, occupations, and regions of India and its neighborhood are how people are assigned nakShastra-s. - MT