In years long ago in the eastern part of upland Diffun, there was a place called Sitio Ganano, after the name of the Ganano River. This sitio was a purok Barangay Cama (now Baguio Village). Notable residents of Sitio Ganano were the Marzo and Agustin families.
With the increase of population after so many years, and because of its distance from the then center of barangay activities, the people here decided to form their own barangay. Led by then Kagawad Jovito Agustin, they declared in 1960 that sitio Ganano become Barangay Don Sergio Osmeña.
Then came the separation of Quirino from Nueva Vizcaya as an independent province. It was under the leadership of Mayor Mariano J. Pimentel and Governor Orlando C. Dulay that in 1970, the name Don Sergio Osmeña was changed to Rafael Palma.
During the first elections in the place, Luis Cayetano became Barangay Captain. He served from 1970 to 1982. Cayetano was followed by Oscar C. Agustin (1982-85), but for unknown reasons he left the place and ventured in some other place. Rodolfo T. Dela Cruz took over his position by law of succession and served the unfinished term until 1986.
Simeon Q. Cayetano followed (1986-95). When Cayetano ran for Municipal Councilor, Diosdado P. Delos Santos served the unexpired term until 1997.
Simeon Cayetano made a comeback (1997-2002); followed by Benjamin P. Agustin (2002-2013).
During the elections of 2013, Diosdado P. Delos Santos also made a comeback; and he serves his constituents as Barangay Captain up to the present.