History of Mediaeval Hindu India (being a History of India from 600 to 1200 A.D.) v1.c14.s6.50

v1.c14.s6.50

The Chālukyas used the Śaka era throughout their supremacy. In fact from 500 A. D. or 422 Śaka (the date of Varāha Mihira's Siddhānta) onwards roughly, the Śaka era is generally used in the south by most kingdoms. The reason probably is that the astronomers of India who propounded the Siddhāntas which are the basis of modern astronomical calculations in India adopted the Śaka era for calculation. According to our view, these Siddhāntas were the result of the study of astronomy at Ujjain with the help and guidance of Greek astronomy (which is plainly incorporated into Indian ancient astronomy) under the rule of the Śakas. Āryabhatta and Varāhamihira and later, Brahmagupta promulgated the new Siddhānta system.