Very good question! Dioscoria is in the western parts of the Indian Ocean. Its traditional spheres of influence are the Mediterranean, the Middle East and the East African coastline. There are more ephemeral connections to other planes of existence , but also to other hidden isles, many of which are closer to Europe. Since ancient times rumours persist that these isles have secret passage ways to each other …
The year being 1562 the entire world is theoretically at play! One can always leave the places where Dioscoria has networks and contacts, its enemies have spread across the globe and so the fight needs to follow them.