The Gaddang language (also Cagayan) is and Austronesian language spoken by up to 30,000 of the Gaddang people in the Philippines, particularly along the Magat and upper Cagayan rivers in the Region II [2] provinces of Nueva Vizcaya[3] and Isabela and by overseas migrants to countries in Asia, Australia, Canada, Europe, in the Middle East, United Kingdom and the United States.

The Dominicans tried to replace the multitude of Cagayan-valley languages with Ibanag, and later the plantations imported Ilocanos workers in such numbers that they outnumbered the valley natives.

Once significantly-Gaddang communities grew exponentially after WWII due to in-migration of Tagalog, Igorot, and other ethnicities; Gaddang is now a minority language.

Mary Christine Abriza wrote "The Gaddang are found in northern Nueva Vizcaya, especially Bayombong, Solano, and Bagabag on the western bank of the Magat River, and Santiago, Angadanan, Cauayan, and Reina Mercedes on the Cagayan River for Christianed groups; and western Isabela, along the edges of Kalinga and Bontoc, in the towns of Antatet, Dalig, and the barrios of Gamu and Tumauini for the non-Christian communities.

By the time you arrive in Santiago City, in-migration due to the economic development of the lower Cagayan Valley over the last century means you now must search diligently to hear Gaddang spoken at all.

"[7] Gaddang uses si in the same manner as the Tagalog sa, as an all-purpose indication that a spatial or temporal relationship exists.