Ba River is an important waterway system in the Southern Central region of Vietnam. Historically, the lower reaches of Ba River (present Phu Yen province) was the area of power struggles among minor states and tribes living along the river basin and the surrounding areas for the control of that important waterway system linking the South Central region and the Western Highlands with the outside world through Da Dien Estuary. Originally, the disputes broke out between the Cham people and other ethnic groups such as the Jarai, the Rhade, the Bahnar, etc... and, in the end, the Cham controlled the lower reaches of Ba River and drove other tribes to the upper course. When the Champa kingdom was founded, Ba River became the buffer zone during the process of dichotomy of that kingdom (territorial dichotomy: Northern Champa Southern Champa
dichotomy between clans: Areca clan-Coconut clan
dichotomy of lineages: ancestors coming from mountains-ancestors coming from the seas). In the fifteenth century, with the appearance of Dai Viet, a Vietnamese dynasty, the Ba River basin became the territories of 3 minor states of Champa, Nam Ban and Hoa Anh. After that land was pacified by the Nguyen Lords, Phu Yen was officially merged into Dai Viet. The role of Ba River in the South Central region was no less important than Thu Bon River and Hoi An Seaport in the north, which the authors can track out and identify issues relating to the history, economy and culture of the Southern Central region and the Western Highlands if adequate studies are carried out.