History of Nadi Palm Leaves – Nadi Astrology In ancient Tamil traditions, there existed people who were highly competent and knowledgeable in disciplines like arts, science, astronomy, literature, drama, and dance.People came to them for advice and to be treated for their medical problems because they were highly sought after and revered in society. They were referred to as Siddhars.With an iron nail known as Olai Chuvadi, the Siddhars would collect their discoveries and studies onto palm leaf manuscripts.