Located in the northeastern section of Luzon,[5] it is composed of five Philippine provinces: Batanes, Cagayan, Isabela, Nueva Vizcaya, and Quirino.

The eponymous Cagayan River, the country's largest and longest, runs through the region, flows from the Caraballo Mountains, and ends in Aparri.

"[9] The exception is Palanan, which was established in 1625 by Spanish forces who arrived by ship from the Pacific coastal town of Baler in Tayabas province (now part of Aurora).

[11] The Atta or Negritos, the first people in valley, were later moved to the uplands or variably assimilated by the Austronesians, from whom the Ibanags, Itawes, Yogads, Gaddangs, Irayas, Malawegs, and Paranans descended - who actually came from one ethnicity.

Various other peoples, mainly the Ilocanos, Pangasinenses, Kapampangans and Tagalogs, as well as Visayans, Moros, Ivatans, and even foreigners like the Chinese, Indians, Arabs, Spaniards and others were further infused to the native Cagayanes to become the modern Cagayano that we know today.

Ilocano settlers already migrated to Nueva Vizcaya (including present-day Quirino) earlier in 1700s also to work on the tobacco plantations, and later immigrants with skills construct churches and other structures needed for development, as the native Igorot tribes rejected labor imposed by the Spaniards.

[19] : "43"  Cagayan Valley became one of the flashpoints of conflict, with many previously-moderate young people joining the armed resistance against Marcos after being radicalized by various crackdowns.

[26] In Isabela, protests erupted when Marcos crony Danding Cojuangco managed to block a Spanish-era grant which was supposed to see the return of Hacienda San Antonio and Hacienda Santa Isabel in Ilagan to local farmers, displacing tens of thousands of farmers who were supposed to get those lands back a hundred years after the Spanish accosted them.

[27] The Roman Catholic Diocese of Ilagan led efforts to support the farmers in their cause, succeeding in forcing the Marcos administration to finally concede land titles to 4,000 farmers, but earning the ire of the dicatatorship against leading church figures such as Ilagan Bishop Miguel Purugganan, Diocesan Social Action Center researcher Sabino "Abe" Padilla, and the various nuns and lay workers of the Diocese.

[28] Also during that time, logging concessions were awarded to Juan Ponce Enrile, Herminio Disini, and other cronies, leading to the severe degradation of forest cover in the region, which contributed to widespread flooding and other environmental issues that persist today.

[29][30] Kalinga-Apayao and Ifugao were transferred to the Cagayan Valley region in 1972, and afterwards Ferdinand Marcos imposed a migration policy for Ilokanos into those provinces; the natives of Apayao called Isnag become minority there.

After the People Power Revolution in 1986, many of the activists who had joined the underground movement against Marcos decided to "surface," as the new administration of Corazon Aquino released political prisoners and initiated peace talks.

[31] However, anti-left sentiment in her new cabinet, which included individuals who had aligned themselves with the Reform the Armed Forces Movement, made the peace process difficult.

During the worldwide COVID-19 pandemic, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus reached Cagayan Valley on March 21, 2020, when the first case of the disease was confirmed in Tuguegarao.

They are ethnically and linguistically diverse, with a substrate of Agtas, Negritos who are food-gatherers with no fixed abodes, overlaid by Ilongots and others in a number of tribes, some of whom were fierce head-hunters (they have given up the practice), with the latest but largest element of the population being the Ilocanos, closely followed by the Ibanags.

[60][61][62][63][64] The city of Tuguegarao is the center of excellence in education, commerce, trade and culture and as the economic center of the region, the city continuously aims for outstanding performance and competence in administration, citizen participation, community and economic development, cultural arts, education, fiscal management, infrastructure, intergovernmental cooperation, planning, public safety, recreation and leisure services, social services, and technology.

The program (Digital Cities 2025) was created through a partnership between the DICT, the IT and Business Process Association of the Philippines (IBPAP), and Leechiu Property Consultants (LPC).

Other support facilities, warehouses and small and big rice mills, strategically located in the different barangays of the city to address the storage needs of farmers during the harvest season.

[78][79][80] Cagayan has several attractions which include beaches, swimming, snorkeling, skin-diving, fishing in the river and the sea, hiking in primeval forest, mountain-climbing, archaeological sites, the collection of the provincial museum, the Callao Caves, and many churches.

Small scale industries like furniture making, basketry, rattan craft, and dried/fossilized flower production, where the province was famously known, are prevalent.

Oranges and mangoes are now major crops being exported fresh to other Asian countries; earning its title as the Citrus Capital of the Philippines.

The recent aquaculture congress found that the growth of tilapia production was due to government interventions: provision of fast-growing species, accreditation of private hatcheries to ensure supply of quality fingerlings, establishment of demonstration farms, providing free fingerlings to newly constructed fishponds, and the dissemination of tilapia to Nueva Vizcaya (in Diadi town).

Based on the data from the Bureau Fisheries and Aquatic Resources in 2020, there are about 1,000 hectares of freshwater ponds in Isabela, producing around 16,000 metric tons of tilapia a year.

Cagayan's deep seas are known for species like tuna, tuna-like fishes, hairtail, snapper, scad, slipmouth, mullet, grouper, shrimp, squid, and lobsters.

[109] The coastal waters of Isabela are big sources of marine life that could supply the fish requirements of the region, according to a study commissioned by the Bureau of Fisheries and Aquatic Resources (BFAR).

The study stated that Isabela waters are rich in untapped fisheries and marine resources and also has extensive sea grass beds and coral reefs that are home to variety of fish species which include sardines and mackerel and have sizable chunks of oceanic tunas, which thrive throughout the year.

Several problems have affected the sector in the recent years including the weather disturbances, use of illegal fishing gears and methods and the increasing demand of a fast-growing population.

[119] Cagayan Valley is positioned to become the country's Citrus Capital through a program undertaken by the Nueva Vizcaya State University (NVSU) with funding from the Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development of the Department of Science and Technology (DoST-PCAARRD).

By the end of 2017, the program team is expected to produce value chain maps for calamansi, orange, and pomelo in the region; characterize fifteen species for the database system of the gene bank study; improve NVSU and Municipal Agriculture Office (MAGRO) citrus nurseries producing 10,000 and 2,000 budded seedlings, respectively; establish new 1-hectare orchard with planting materials from NVSU; and generate data on the description of local citrus pests and diseases.