Kalinga (province) in the context of Lubuagan

The Chico River (Spanish: Río Chico de Cagayán), is a river system in the Philippines in the island of Luzon, encompassing the regions of Cordillera and Cagayan Valley. It is the longest tributary of the Cagayan River with a total length of 233 km (145 mi).

The most extensive river in the Cordillera region, it covers the provinces of Mountain Province, Kalinga and Cagayan. It is referred to as a "river of life" for the Kalinga people who live on its banks, and is well known among development workers because of the Chico River Dam Project, an electric power generation project which local residents resisted for three decades before it was finally shelved in the 1980s - a landmark case study concerning ancestral domain issues in the Philippines.

Cagayan (/kɑːɡəˈjɑːn/ kah-gə-YAHN, [kagɐˈjan]), officially the Province of Cagayan (Ilocano: Probinsia ti Cagayan; Ibanag: Provinsiya na Cagayan; Itawit: Provinsiya ya Cagayan; Isnag: Provinsia nga Cagayan; Ivatan: Provinsiya nu Cagayan; Gaddang: Provinsia na Cagayan; Filipino: Lalawigan ng Cagayan), is a province in the Philippines located in the Cagayan Valley region, covering the northeastern tip of Luzon. Its capital is Tuguegarao, the largest city of that province as well as the regional center of Region 2 (Cagayan Valley). It is about 431 kilometres (268 mi) northwest of Manila, and includes the Babuyan Islands to the north. The province borders Ilocos Norte and Apayao to the west, and Kalinga and Isabela to the south.

Cagayan was one of the early provinces that existed during the Spanish colonial period. Called La Provincia de Cagayan, its borders essentially covered the entire Cagayan Valley, which included the present provinces of Isabela, Quirino, Nueva Vizcaya, Batanes and portions of Kalinga, Apayao, and Aurora. The former capital was Nueva Segovia, which also served as the seat of the Diocese of Nueva Segovia. Today, only 9,295.75 square kilometres (3,589.11 sq mi) remain of the former vastness of the province. The entire region, however, is still referred to as Cagayan Valley.

Apayao, officially the Province of Apayao (Ilocano: Probinsia ti Apayao; Itawit: Provinsiya ya Apayao; Isnag: Provinsia nga Apayao; Tagalog: Lalawigan ng Apayao), is a landlocked province in the Philippines in the Cordillera Administrative Region in Luzon. Kabugao serves as its capital. The provincial capitol and its associated offices are located at the New Government Center in Luna.

The province borders Cagayan to the north and east, Abra and Ilocos Norte to the west, and Kalinga to the south. Prior to 1995, Kalinga and Apayao comprised a single province named Kalinga-Apayao, which was partitioned to better service the needs of individual ethnic groups.

Abra, officially the Province of Abra (Ilocano: Probinsia ti Abra; Inlaod Itneg: Probinsiya ta Abra; Maeng Itneg: Probinsiya di Abra; Moyadan Itneg: Probinsiya ti Abra; Filipino: Lalawigan ng Abra), is a province in the Cordillera Administrative Region of the Philippines. Its capital is the municipality of Bangued, the most populous in the province. It is bordered by Ilocos Norte on the northwest, Apayao on the northeast, Kalinga on the mid-east, Mountain Province on the southeast, and Ilocos Sur on the southwest.

Tuguegarao (/tʊˈɡɛɡəraʊ/ or /tʊɡɛɡəˈraʊ/), officially the City of Tuguegarao (Ibanag: Siyudad nat Tugegaraw; Itawit: Siyudad yo Tugegaraw; Ilocano: Siudad ti Tuguegarao; Filipino: Lungsod ng Tuguegarao [tʊgɛ̝gäˈɾaʊ]), is a 2nd class component city and capital of the province of Cagayan, Philippines. According to the 2024 census, it has a population of 167,297 people, making it the most populous city in Cagayan Province, Cagayan Valley and Northeastern Luzon.

A major urban center and primary growth center in the Northeastern Luzon, it is the regional center of Cagayan Valley and also its regional institutional and administrative center. The city is a convergence area for the provinces of Cagayan, Kalinga, Apayao and northern Isabela and one of the fast-emerging cities in the Philippines.

Isabela, officially the Province of Isabela (Ilocano: Probinsia ti Isabela; Ibanag: Provinsia na Isabela; Tagalog: Lalawigan ng Isabela), is the second largest province in the Philippines by land area located in the Cagayan Valley. Its capital and the largest local government unit is the city of Ilagan. It is bordered by the provinces of Cagayan to the north, Kalinga to the northwest, Mountain Province to the central-west, Ifugao and Nueva Vizcaya to the southwest, Quirino, Aurora and the independent city of Santiago to the south, and the Philippine Sea to the east.

This primarily agricultural province is the rice and corn granary of Luzon with its mix of plains and rolling terrain. In 2012, the province was declared as the country's top producer of corn with 1,209,524 metric tons. Isabela was also declared the second-largest rice producer in the Philippines and the "Queen Province of the North".

The Cordillera Central or Cordillera Range is a massive mountain range 320 kilometres (200 mi) long north–south and 118 kilometres (73 mi) east-west situated in the north-central part of the island of Luzon, in the Philippines. The mountain range encompasses all provinces of the Cordillera Administrative Region (Abra, Apayao, Benguet, Ifugao, Kalinga and Mountain Province), as well as portions of eastern Ilocos Norte, eastern Ilocos Sur, eastern La Union, northeastern Pangasinan, western Nueva Vizcaya, and western Cagayan.

To the north, the mountain range terminates at the northern shores of Luzon along the Babuyan Channel in Ilocos Norte and Cagayan provinces. At its southeastern part, the Central Cordillera is linked to the Sierra Madre Mountains, the longest mountain range in the country, through the Caraballo Mountains in Nueva Vizcaya province. During Spanish colonial period, the whole range was called Nueva Provincia (New Province).