Pamplona is a fourth class municipality in the province of Cagayan, Philippines. According to the 2010 census, it has a population of 23,236 people.HistoryPamplona is the result of the fusion of two villages; Abulacan (now barrio San Juan) and Masi. Abulacan was founded by the ecclesiastical authorities on April 30, 1757 with San Juan Nepomuceno as the patron saint. Sometime in 1842, Vicar Pedro Montenegro, O.P. convinced the people to unite the two towns.