Tibetan Astrology originated from several different traditions: Indian, Chinese, the local Bon religion, and the Buddhist Kalachakra tantra.
Traditionally, astrology was one of the five secondary sciences in Tibet. It concerns not only divination, but it is also used in the study of time cycles, Tibetan chronology and the compilation of the calendar. The calendar in the form of an almanac is still quite important in the daily life of the Tibetans to ensure that their daily activities are in tune with the cosmos.
In general, certain days of the week and of the month are considered auspicious for specific activities (from marriage to hanging of prayer flags - even cutting one's hair); but also, every day relates to one's specific astrological chart of the day of birth. But also the position of the planets and the cycles of the elements determine good or bad fortune.
In a Tibetan village, the astrologer would use his skills to advise people about nearly everything: from the weather, the best time to harvest, verify if and when two people should marry, to important business deals. In case the outcome would be negative, often religious practices would be advised to remove obstacles, which would be carried out by monks of the local monastery.
At the birth of a child, the charts would be checked to see if any special rituals were required to ward off negative planetary influences. Also a "death chart" would often be prepared to decide the exact performance of the funeral. Improper performance could result in problems for the family, as well as for the deceased.
Tibetan astrology is not only strongly linked to religion, also Tibetan medical practitioners would study astrology (and religious texts) to determine the timing of medication etc.
Tibetan 'Naktsi' astrology has mainly Chinese origins, and the 'Kartsi' astrology has Indian origins.
TIBETAN 'NAMELESS RELIGION' ORIGIN
From the ancient 'nameless religion' of Tibet, a system is preserved in current Tibetan astrology which relates to Five Individual Forces (La - vitality, Sok - life potential, Lu - bodily health, Wangthang - personal power, and Lungta - wind horse) or energies within a person. These energies relate to the Chinese animals and elements, for example, the La force of the Horse is Wood etc. This system is unique to Tibet and is important to establish yearly horoscopes.
The La moves through the body in a monthly cycle, the Wangthang element is the same element that rules the year in Chinese astrology.
When the forces become weak, numerous specific practices are prescribed to strengthen the force again, from saving lives of animals to reciting mantras or performing special rituals like exorcism.