The most important event in the history of Cagayan Valley took place in 1572 when Spanish Conquistador Don Juan de Salcedo traced the northern coast and landed at the mouth of the Pamplona River. Before his visit, early Cagayanos reveled in a civilization of their own.
The Spanish occupation in Cagayan was recorded to have started in 1581 when Gobernador Gonzalo Ronquillo de Penaloza sent Juan Pablo Carreon to the north to drive away a Japanese fleet under the command of Taifusa. Carreon succeeded in his mission and proceeded upriver to look for future pueblo sites and thus making a name for himself in the process.
Lal-lo-c(old name of Lallo), one of the first four (4) cities in the Philippines(others: Manila-I571;Cebu-1565; Naga-1575) was named Ciudad Nueva Segovia in 1581 by Carreon. It was chosen as capital of Cagayan Valley Region because of its favorable location and navigable river. It was also the seat of the Diocese created by Pope Clement VII on August 15, 1595 until the seat was transferred to Vigan, Ilocos Sur in 1755. Very famous among the missionaries at that time was Bishop Miguel de Benavidez, OP, the first bishop elected to the Diocesan home in Ciudad Nueva Segovia. He later founded the University of Sto. Tomas.
It was from Lallo that authorities governed the province and was the capital of Cagayan up to 1839 when Cagayan Valley Region was subdivided. On May 24, 1839 the province of lsabela was created comprising the towns of Cordon to Ilagan, including the sitio of Palanan. Nueva Vizcaya comprised the region from Aritao to Bayombong and later to Diadi. Cagayan comprised that part of the valley from Tuguegarao to Aparri and the Babuyanes. And the provincial government was moved to Tuguegarao from Lal-lo.
Cagayan Valley abounds with natural resources and exudes with development potentials that consist of rich agricultural areas, forestland and grasslands, inland and marine resources.
Geographically, the valley is located at the northeastern part of mainland Luzon covering an area of about 26,858.79 square kilometers making it the 2nd largest region in the country. Bounded with the Pacific Ocean in the east and the protective mountain range of Cordillera on the west and Caraballo Mountain, the provinces of Nueva Ecija and Aurora on the south. Between the ranges is the valley where most of the population live and is criss-crossed by the mighty Cagayan River, the longest and widest in the country and its tributaries, which flow into the Babuyan Channel in Aparri. The Pacific Ocean on the east cost and the Babuyan Channel on the north also skirt the mainland.The Batanes group of island is located at the northernmost tip of the Philippine Archipelago surrounded by Bashi Channel on the north, Pacific Ocean on the east, Balintang Channel on the south and China Sea on the west.
It has more than 890 kilometers of coastline and rich fishing grounds, particularly with the Babuyan and Balintang Channels on the north and the Palanan and Divilacan Bays on the east including its territorial seas within the 200 kilometer Exclusive Economic Zone (EEZ). The region has four (4) minor volcanoes with several inactive fault lines, which include the Digdig Fault. The climate in the valley falls under Type 3 characterized by not very pronounced seasons - relatively dry from November to June and wet during the rest of the year.
Cagayan Valley Region is composed of five provinces - Batanes, Cagayan, Isabela, Nueva Vizcaya and Quirino and three cities - Cauayan, Santiago and Tuguegarao. The region's population based on the year 2000 census of the population was 2,813,159.