It primarily centers around the Hindu god Shiva and goddess Parvati, but references and reveres all gods. The Shiva Purana asserts that it once consisted of 100,000 verses set out in twelve samhitas (books), however the Purana adds that it was abridged by sage Vyasa before being taught to Romaharshana. The Shiva Purana contains chapters with Shiva-centered cosmology, mythology, relationship between gods, ethics, Yoga, Tirtha(Pilgrimage) sites, bhakti, rivers and geography, and other topics. The text is an important source of historic information on different types and theology behind Shaivism in early 2nd-millennium CE. The oldest surviving chapters of the Shiva Purana have significant Advaita Vedanta philosophy, which is mixed in with theistic elements of bhakti.