About 300 years ago, Davao Oriental was merely a part of Caraga Province, forming part of the Encomienda de Bislig with the Encomienda de Seargao, Butuan, and Tandag. The province became historically important in 1846, when a distinguished Attorney-at-Law, Don Jose Uyanguren, upon the order of Gov. Narciso Claveria, organized settlements with considerable inhabitants south of the Encomienda de Bislig. Today, these are the municipalities of Baganga, Governor Generoso and Mati.
As the settlement continued to grow, Don Jose was able to crush Datu Bago, a Bagobo chieftain who ruled Samal Island and marked his conquest on the vast lush region beyond the island. In February 27, 1849, Gov. Claveria decreed the partition of Caraga province in two. The northern portion was named Surigao Province, with Surigao town as the capital, and the southern part of Eastern Mindanao, including Davao Gulf, was named Nueva Guipozcoa in honor of his natal town in Spain with Caraga Town as its capital. But, for expediency in matters of administration, Nueva Guizpozcoa was placed under the direct supervision and control of Commandancia de Bislig. Later, Nueva Guipozcoa was renamed Davao.
In 1898, Davao became a district of the Moro Province created as part of Mindanao by the Americans with General Leonard Wood as its first Military Governor and in 1916, Jones Law converted Moro province into the Department of Mindanao and Sulu – all districts comprising the Department became a regular province. Don Gulalio Causing became the first Provincial Governor.
Eastern Davao, the “Contra Costa” remained only a promise to the administration, and from August 31 to September 3, 1924, the Municipal Presidents of Cateel, Baganga, Manay and Mati approved a resolution favorably endorsed by the council of member municipalities petitioning the higher authorities concerned to declare Eastern Davao as a sub-province to be called Plaridel.
In 1956, Congressman Ismael Veloso of Davao passed a bill in Congress creating Davao del Sur Province. He proposed the separation of the municipalities of Lianga, Hinatuan, Bislig and Lingig from Surigao Province to be combined with Contra Costa towns. Unfortunately, the bill failed to get the approval of the Senate. He then passed another bill dividing Davao into three provinces. The bill was approved in the Lower House but failed to get the approval of the Senate. Congressman Lorenzo Sarmiento revived the bill in 1965. This time, with the blessing of Senator Alejandro Almendras, the bill finally got the approval of both chambers and became Republic Act 4867. This Republic Act brought into existence the Province of Davao Oriental.