Barangay Gulac is situated Northern of Diffun, more or less 6 kilometers from the town proper, with access road along the national irrigation canal. It lies at the boundary between Diffun and Santiago City.
Barangay Gulac obtained its juridical personality in 1950 by virtue of RA 4754. But in times past it was a forested plain of seemingly unlimited natural resources. There it was wild games in abundance and lush vegetation.
Legend has it that the first inhabitant of the place was a brave Ilocano by the name of Pedro Gadia, Sr. the man pioneered in clearing the area and planted it to different kinds of fruit trees and vegetables.
Happy with his successful exploits in the land, he brought his family to settle in the area. He had the magnanimity to invite his friends to also reside in the fertile grounds that he had discovered.
The story goes on to say that as Pedro Gadia, Sr. exhorted his friends to go to the area, telling them about the bright future that awaited those who dared to go there, an American visitor who happened to be listening to the conversation blurted out an encouragement to the small crowd, saying “go there and find your luck!”
Many of Pedro friends who did go to the settlement remembered what the foreigner said to them, but recalling only the first and last words do and luck. Somehow those two words stuck in their minds, and they began referring to the settlement as go-luck. The words eventually became the name of the place.
Pedro Gadia, Sr. became every ones natural choice to lead the group.
He became their first Teniente Del Barrio.
Many barangay leaders followed suit after him; and with countless efforts among its residents to improve their individual stature, the barangay will definitely advance from one progressive eco-socio-political activity to another.