Varahamihira compiles the Pancha-siddhantika

The Pancha-siddhantika sets out, with Varahamihira’s own additions, the methods of five systems: the old Paitamaha, which he found the least accurate, the Vasishtha, the Paulisha and the Romaka — the last two of Greek origin; the Romaka counts its days from sunset at Yavanapura, that is, Alexandria — and the Surya, which he judged the most accurate. It contains sine calculations and trigonometric relations. His Brihat-samhita, which by its own count has a hundred chapters, is an encyclopaedia of divination: the motions of the planets, eclipses and weather omens alongside architecture, gems, perfumes, horses, the care of trees and agriculture. In its second chapter he remarks that the Greeks (yavanas), though barbarians, are honoured like sages for their mastery of this science. He also wrote the Brihajjataka and the Laghujataka on horoscopy, and works on military expeditions and on marriage.

The date of the Pancha-siddhantika is uncertain. Its epoch is the year 505, and Otto Neugebauer and David Pingree bound Varahamihira’s date by that epoch and by Brahmagupta’s knowledge of his work in 628. Many reference works date the treatise to about 575, while some take 505 as the year it was written or begun; the later commentator Amaraja put Varahamihira’s death in 587. Pingree describes him as a native of Avanti, the region around Ujjain, who lived in the village of Kapitthaka. The tradition that he was one of the ‘nine jewels’ at the court of King Vikramaditya comes from a late literary forgery; a connection with Yashodharman’s court at Dashapura has been suggested but not proved. In the 11th century al-Biruni quoted the Brihat-samhita.