 The Sa Huỳnh culture showed evidence of an extensive trade network that existed between 500 BC to AD 1500, known as the Sa Huynh-Kalanay Interaction Sphere (named after the Sa Huỳnh culture and the Kalanay Cave of Palawan, Philippines).It was mainly between Sa Huỳnh and the Philippines, but also extended into archaeological sites in Taiwan, Southern Thailand, and northeastern Borneo.It is characterized by shared red-slipped pottery traditions, as well as double-headed and penannular ornaments known as "lingling-o" made from materials like green jade (sourced from Taiwan), green mica (from Mindoro), black nephrite (from Hà Tĩnh) and clay (from Vietnam and the Northern Philippines).