In 1951, the barrios of Magallon, Odiong and Guinpanaan, then belonging to the town of Isabela, were separated to form the town of Magallon. The boundary between the two towns were as surveyed by the Bureau of lands in accordance with Resolution No. 1. of the joint session of the Provincial Board of Negros Occidental and the Municipal Council of Isabela dated November 15, 1949, and subsequently concurred to by Resolution No. 79 of the Municipal Council of Isabela dated December 26, 1949.