The Gaddang (Gadan, Ga'dang, Gaddanes, Iraya, Pagan Gaddang, Yrraya) live in the middle Cagayan Valley in northern Luzon, the Philippines. "Gaddang" refers to both the Christianized Gaddang who are now largely assimilated into Ilocano or general Filipino society and the Pagan Gaddang. In the 1960s, there were about 2,500 Pagan Gaddang and 25,000 Christian Gaddang. Their combined number in 1975 was estimated at 17,500, suggesting continuing assimilation into mainstream Filipino society.
Wallace, Ben J. (1969). "Pagan Gaddang Spouse Exchange. Ethnology 8:183-189.