[3] Established in the year 1600, Casiguran was the first missionary parish of Sorsogon.

When the Spaniards first set foot in this part of Luzon in the 1570s, Casiguran was considered as their center of Kabikolan.

The first is from the name of Gugurang, the supreme deity of the indigenous peoples of Bicol (called Ibalon during the pre-colonial era).

A second is a folk legend, which narrates that the name is phonetically derived from the Bikol phrase 'kasi gurang' (literally translated, "because old") as it is Sorsogon's ancient kingdom.

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