section_path: History
section_name: History
paragraph_text: History
  
  During the time of the Tibetan Empire, the twelve months were named according to the four seasons of the year, and the year started in spring.
  
  Tibetans historically used the Indian astrological system, Tib. kar rtsis, that divided the days into rhythms defined by the elements and the constellations, and later used a Chinese astrological system, Tib. byung rtsis, which focuses on twelve animals and the five elements to describe patterns of events. The Indian and Chinese systems were joined by the Buddha 's teachings found within the Sutra Avatamsakra and the Tantra Kalachakra to develop the Tibetan astrological calendar.
  
  Beginning in the 12th century, the years were named after the 12 animals common in the Chinese zodiac.
  
  The translation of the Kalachakra Tantra in the late 11th century CE marked the beginning of a change of Tibet's calendar. This tantra references the Indian astronomical calendar system with its calculations that follow the progression of the constellations - the five planets, and the sun and moon eclipses.
  
  As the original teachings of the Kalacakra were taught by the Buddha himself, two hundred years later, the Kalacakra calendar was officially adopted as a Tibetan calendar by the Ü-Tsang king Drogön Chögyal Phagpa, in the second half of the 13th century.
  
  A distinct Tibetan calendar was developed in 1284 by the lineage of the Gyalwang Karmapas, the Tsurphu tradition calendar. This Tsurluk calendar is based on the 3rd Karmapa, Rangjung Dorje's astrological treatise called The Compendium of Astrology (Tib. rtsis kun bsdus pa), a treatise from which many later treatises authored by the subsequent Karmapas and by Jamgon Kongtrul the Great evolved. The Tsurluk calendar is still overseen by Tsipa Gelek Dhargay, at the 17th Karmapa, Ogyen Trinley Dorje's seat in Rumtek, Sikkim, India.
  
  In 1447, a Tibetan astrologer Phukpa Lhündrub Gyatso composed an astrological treatise called The Oral Teachings of Pundarika (Tib. pad dkar zhal lung). His work founded the Phukpa calendar which is the main calendar of Tibet. This main Tibetan calendar, the Phukpa, was modified many times during the subsequent centuries, and it remains a luni-solar calendar.