Before 2nd century B.C.

In the ancient times, the shamanistic Bön religion was the main cult in Tibet, and Elemental astrology was already practiced, but only a little is known of its original form. There was already knowledge of the five elements Wood, Fire, Earth, Iron and Water and the phases of Moon and Sun. The divination and prediction system was shamanistic with black and white magic, exorcism, sacrifice of animals and human blood letting.

2nd century B.C. - 4th century A.D.

During the reign of Tibet's first king, Nyatri Tsenpo (who ascended the throne in 127 B.C.)twelve major Bön doctrines were created with a detailed system of categories and sub-categories. Astrology and medicine were among those categories.
In time more knowledge of astrology developed, but it is difficult to place the timing of it. Bön astrologers connected the five elements together with Srog (lifeforce element), Lus (body - health element), Wangthang (empowering force) and Lungtha (success element). They also observe nine magic Mewa square numbers, and the system of twelve animal years started to form. From China comes the principle of eight Parkha trigrams (also known from I Ching).

4th century A.D

The first Buddhist teachings and scriptures came to Tibet and also bought advances in astrology and astronomy.

Source: Taina Kumpulainen