Camarag was the popular in the 18th century when names such as Echague and San Isidro, where not yet known. During this the Spanish period, Camarag was derived from the Camarag trees abundant in this place. A big Roman Catholic Church and road connection Camarag to other places like Santiago to Vizcaya were constructed and it was the site of the mission under the Dominican order in 1710. The ruins of this landmark are still there at present.
Camarag because a town of the province of Cagayan in the year 1776. It was love province in the Cagayan Valley at that time, However in the year 1839 Camarag become the capital of Nueva Vizcaya when this province created, In 1856, 17 years later it becomes at town of Isabela, these 3 provinces composed then the Cagayan Valley Region, Camarag was the one of the original town of Isabela, the others were Cabagan, Tumauini, Ilagan, Gamu, Cauayan, Angadanan, Carig, (Santiago), Palanan, Alamo, Gaddang, Mayaoyao, Brengiones and Cataloganes.
Camarag was town of many years until the town site was transferred to Katuray. A place near the Cagayan River and the present town of Echague. The transfer took place in the year 1863. Katuray become Echague in Honor of Gen. Rafael D. Echague then the Governor General in the Country with the transfer at town site to Katuray Camarag become a barrio of Echague, however in the year 1967, 104 year later San Isidro was created a separate Municipality.
On the whole, it could be aid that the Camarag was the mother of Echague which eventually become the mother of San Isidro.
Legal basis for the creation of barangay :Dominicant Order in 1710