This edited volume is an important text of ninth century India. From Paitāmaha Siddhānta, siddhāntic age began and it continued up to Siddhānta Sundara of Jnānraja of 14th century CE. Before compilation of Brahmasiddhānta in Śākalyasaṁhitā a series of astronomical texts had been published, like Ᾱryabhatiya, Laghu Bhāskariya, Mahā Bhāskariya, Brāhmasphutasiddhānta etc. Brahmasiddhānta in Śākalyasaṁhitā contains all the contemporary astronomical knowledge of India. Any reader having preliminary knowledge on astronomy can understand the contents of this volume. Peculiarities of this book are- a. Chapter division is not in the conventional way; b. Manuscripts do not show the name of the chapters; c. Name of the compiler was found at the end of the chapter; This book contains eight chapters and 764 verses in which third chapter contains ritual time measurements, effect of religious rituals etc. This compilation was noticed by eminent figures like S B Dikshit, David Pingree and many others.