Around 1818, San Fabian had a boundary dispute with Mangaldan. The boundary between the two towns was the Angalacan river, which sometimes overflows because of floods. The boundary dispute was settled in 1900, when the mayor of San Fabian agreed to meet the mayor of Mangaldan and the two reached an agreement with a boundary marker being erected at Longos between the towns of San Fabian and Mangaldan. The agreement was signed by Juan Ulanday, Nicolas Rosa, Vicente Padilla, Marcelo Erfe, and approved by the American Commander Capt. Ferguson.