There is something special about having a tree as the main thing that draws people to a place. The island of Mannar in Sri Lanka is one of the few spots that can make that claim. The island has a long history of pearl fishing that dates back to at least the second century. Mannar came to be renowned for its pearls, among other resources, and its location on a thriving trade route attracted merchants from Europe and the Middle East. Oral history has it that an Arab merchant brought…