Anao was a handsome, strong hunter who fell in love with Aon, the most beautiful woman and daughter of a powerful datu, who ruled the town, which was formerly a barangay.

The datu wanted to break their love, however, he failed since the lovers were found dead near the riverbank in cold embrace.

During the Spanish–American War, the town was almost reduced to ashes hence, it was reverted into a barrio until the earlier part of 1957.

1768, approved May 20, 1971 by the House of the Senate, its unique and indigenous name Anao-aon was changed into San Francisco in honor of the Patron Saint, Saint Francis Xavier only to find out that it was creating confusion because there are many municipalities in the Philippines already named after San Francisco, but then it's too late for its politician authors and supporters to make the move to revert into its original name of Anao-aon.

Poverty incidence of San Francisco Source: Philippine Statistics Authority[10][11][12][13][14][15][16][17]