Between 1818 and 1902, the Province of Aurora, then a district of "El Principe", Nueva Ecija consisted only of Baler and Casiguran. The four (4) other existing municipalities were just mission villages like the San Jose de Casecnan (now Maria Aurora), Dipaculao, Dilasag and Ditale. While what is now the municipality of San Luis was a "barrio" of Baler adjacent to the old barrios of Real, Bacong, Ditumabo and Zarah. It was named after the patron Saint "San Luis Rey de Francia".