 Prior to gaining separate representation, areas now under the jurisdiction of Davao de Oro were represented under the Department of Mindanao and Sulu (1917–1935), Davao Province (1935–1967), Region XI (1978–1984) and Davao del Norte (1967–1972; 1984–1998).The passage of Republic Act No.8470 and its subsequent ratification by plebiscite on 7 March 1998 separated from Davao del Norte's first and second districts a total of eleven municipalities to create the new province of Compostela Valley (now named Davao de Oro), which itself was apportioned into two new congressional districts.