The Gaddang are an officially-recognized indigenous people and a linguistically-identified ethnic group. For centuries, they have inhabited the Northern Luzon watershed of the Cagayan River and its tributaries, and maintained a distinct identity from their neighbors.

Gaddang speakers were recently reported to number as many as 30,000; that number does not include another 6,000 related Ga'dang speakers or any of several other small linguistic-groups whose vocabularies were determined to be more than 75% identical.

These proximate groups, mutually-intelligible but speaking with phonetically-varying accents, include the Gaddang, Ga'dang of Alfonso Lista and Tabuk, Baliwon of Paracelis, Cauayeno, Katalangan in San Mariano, Yogad around Echague. It is closely related to the speech of Malaweg in Rizal and Itawit of Tuao near the mouth of the Chico river (possibly related to the historically-documented tongue formerly spoken by the Irray of Tuguegarao).

These groups are depicted in current official literature and history as a single people. During the American period, cultural distinctions were asserted between (a) Christian residents of the Isabela plains and Nueva Vizcaya valleys, and (b) formerly non-Christian residents in the nearby Cordillera mountains. Some reporters have exaggerated one or more of those differences, while others may completely ignore or gloss them over.

The Gaddang are indigenous to a compact geographic area; the stage for their story is an area smaller than Metro Manila — about three-quarters of a million hectares. Distances between major population centers: Bayombong to Ilagan=120 km, Echague to Natonin=70 km. The living population collectively comprises less than one-twentieth of one percent (.0005) of Philippines inhabitants, and shares their 0.25% of the nation's land with Ifugao, Ilokano and others.

As a people, Gaddang have no record of expansionism. They created no unique religion or overweening set of beliefs, nor have produced any notable government. Gaddang cultural-identity is determined by their language and to a lesser degree was shaped by their location. However, they have historically implemented social mechanisms to incorporate as full members of their communities individuals born to linguistically-different peoples.

The Cagayan Valley (with its major tributaries Magat, Ilagan, the Mallig and Siffu of the Mallig Plains, and the Chico which joins the Cagayan just 30 miles from the sea) is cut-off from the rest of Luzon by mile-high forested mountain ranges joined at Balete Pass near Baguio. The terraced Cordilleras close in from the west, the darker reaches of northern Sierra Madre arise in the east, meeting at the river sources in the Caraballo Mountains.

Once covered in continuous rainforest, today the valley-floor is a patchwork of intensive agriculture and mid-size civic centers surrounded by hamlets and small villages. Even remote locations in the surrounding mountains now have permanent farm-establishments, all-weather roads, cell-phone towers, mines, and regular markets. Often, native forest-flora has vanished, and any uncultivated areas sprout invasive cogon or other weeds.