Synopsis A landmarking publication by Dr. S.S. Lishk who is widely known for his publications in reputed journals both in India and abroad. This work is an unique contribution which deals with mathematical analysis of ancient Indian astronomy. It covers the post Vedanga and pre-Siddhantic period the so called Dark Period and hither to remaining as a forgotten chapter in history of ancient Indian mathematics and astronomy. This work initiates the task of bridging a big gap between the periods of Vedanga Jyotisa and Siddhantic astronomy in ancient India. Exposition has been made to clarify several links in unearthing the systematic emergence of ancient Indian astronomy right from Jyotisa Vedanga to Siddhantic astronomy. Certain peculiarities of Jaina School of astronomy bear no parallel as hither to known to any western school of astronomy. Consequently Pingree’s views about Mesopotamian origin of ancient Indian mathematical astronomy seems questionable. The work thus poses the problem of source.