The essay at hand deals with some fundamental historical milestones in Siddha medicine as a means to further understand the development of one major medical tradition that is practiced beyond India and Sri Lanka. This paper is situated in a particular framework that is characterized by its manifold transnational dimensions that become apparent in Siddha medicine, but which are also of significance in many other medical practices in the present time. This includes medical traditions such as Ayurveda, Traditional Tibetan Medicine, or acupuncture which continue to spread across national borders and establish themselves in new regions of the world, while usually having been transformed in one way or the other during these transnational transfers. Siddha medicine serves as a helpful example by which a look into the past facilitates the understanding of some of the processes and motives behind such phenomenona as transnational movements of medical traditions which bring forth the plurality and diversity in medical history.