[3] The municipality was named after Spanish governor-general Rafael María de Aguilar, who ordered the establishment of an independent civil political unit on 16 July 1805.

It was hunter's paradise with deer roaming here and there with an occasional wild boar making an appearance.

The grass in the plains were succulent fare for fattening cattle and the water from the brooks and streams clear and sparkling.

Through these river systems, boats sailed from the Ilocos provinces in the North southwards to Dagupan, Calasiao, Lingayen and sometimes even as far as San Isidro De Labrador, Salasa, Aguilar and Camiling.

When the Spaniards in Lingayen heard of this flourishing village, they sent Spanish explorers through the town of Salasa to visit the place.

A petition was therefore, filed with the principales or municipal officials of Binalatongan to convert the village into a town.

However, it was not until 19 January 1806 that the Provincial Governor of Pangasinan was able to make the trip to the sitio of Balubad, the site of the Poblacion, to carry out the provisions of the decree.

The necessary boundary markers were placed and operations were witnessed by the town officials of Salasa and San Carlos.

Local folklores likewise maintained that Aguilar was identified with an eagle or agila that used to fly around the place at nighttime and would perch on a fence or alar when tired of flying, hence, agila and alar put together formed Aguilar.

The Gobernadorcillo also had to procure building materials from the town if possible; if not he had to send a request for approval to the Superior Government in Manila through Alcalde Mayor.

Aguilar is also engages in Poultry and Livestock Raising including Cows, Pigs, Carabaos, Goats, Chickens and Domestic Ducks.