The majority of people living in Cagayan are of Ilocano descent, mostly from migrants coming from the Ilocos Region. Originally, the more numerous group were the Ibanags, who were first sighted by the Spanish explorers and converted to Christianity by missionaries, the reason why the Ibanag language had spread throughout the valley region prior to the arrival of the migrating Ilocanos. Cagayan is predominantly Roman Catholic with 85% of the population affiliated and the Aglipayan Church has a very strong minority in the province.