Parāśara Jyotiṣa has its roots in the Bṛhat Parāśara Horā Śāstra (BPHS). The actual date of this book is not known, but experts estimate this to about 5000+ years ago. It is possible that much of the shlokas have been lost over the period of time. Currently, Bṛhat Parāśara Horā Śāstra contains about 97 chapters spanning 2000+ verses or shlokas. Others who have expanded on this book are Varahamihira, Saravali, Jataka Parijata, Phaladeepika, etc.