During the Spanish Era, the municipality was only a component barrio of Gapan. When San Isidro became a town and was separated from Gapan, the town and San Antonio became one of its component barrios. When San Antonio itself became a town, the area was still its component barrio called San Agustin. By 1865, Jaen was known by its old name "Ibayong Ilog", and because there were many people in the river port in what is now Barangay Langla, the town became a centre for trade.
When the place improved and its population grew to no less than 5,000 people, it became a town through a petition filed by the inhabitants through the initiative of two early leaders, Kabesang Prudencio Esquivel and Kapitan Antonio Embuscado. On June 18, 1865, Jaen itself partitioned from San Antonio, and retained Saint Augustine of Hippo as its patron saint. The Spanish officials signed the papers granting the petition that "Ibayong Ilog" be a town in Factoria (now San Isidro) which was then the capital of Nueva Ecija. The declaration was brought to Governor-General Juan de Lara e Irigoyen in Manila, and afterwards was submitted to the Vice-General of the Philippines in the person of Rev Gregorio Martínez. Father Martínez marked the document as approved but later wrote in his own wish that the name "Ibayong Ilog" be changed to the name of his birthplace of Jaén, Spain.
In coordination with Rev Estanislao B. Moso, Kabesang Prudencio and Kapitan Antonio led the establishment of the first Catholic church (the present-day parish church). Jaen is in Central Luzon, in the southern part of Nueva Ecija. About 100 km from Manila via the old Cagayan Valley Road, the town has other road networks connecting it to Nueva Vizcaya, Isabela, Pampanga, Olongapo and Bataan. In the olden days, Pampanga River was once the only and the fastest way of transportation in going to Manila and other places.
On August 24, 1896, its people revolted against the Spaniards and in September of the same year, armed with bolos and spears, ambushed and killed forty Spanish soldiers in Lumanas (now a Sitio of Barangay Santo Tomas South). This successful attack made Lumanas a historical site called "Pinagtambangan", where a marker was erected in memory of the event.
The municipality is situated in the southern part of Nueva Ecija, some 100 kilometres (62 mi) north of Manila. Jaén is bounded by the municipalities of Santa Rosa on the north-east; Zaragoza on the north-west; by San Isidro on the south; San Leonardo on the east and by San Antonio on the west.
The municipality has a land area of 10,254 hectares (25,340 acres) and is divided into 27 barangays, two of which are in the Población proper.
Most of the north-western section of the municipality is devoted to rice farming, as rice production is the main livelihood of the populace. Twenty barangays of Jaén are fully irrigated, with about 80% of the land (approximately 9,500 hectares) being suited for rice production.
Mango plantations are found in the southern portion of the municipality. Based on the latest survey, 584 hectares are utilized for mango production, including backyard mango farms. Ten percent of the total agricultural area is for planting vegetables.
In the Población and nearby barangays, several establishments have sprouted. These include agricultural supply traders, dry goods stores, hardware stores, groceries, travel agency, fashion style, pawnshop, banks, supermarkets, gasoline stations, printing presses, and eateries. The public market is in the area.
Among the service businesses in the area are pawn shops, restaurants, auto and motorcycle parts and service, car wash, commercial center, lechon manok and liempo stand, pharmacies, computer repair shops, convenience store, bakery, petrol station, grocery, internet café, tailoring and dress shops and rural banks.
Distilled and purified water processors, mobile phone card dealers, cable and landline telephone businesses are also present in the municipality.
Professional services of doctors, accountants, dentists, lawyers, surveyors and engineers are also prevalent in the town. Most of the unemployed and out-of-school youths are given manual labor by private contractors and the local government unit, such as construction workers and street sweepers.
Lolita Ilao Memorial Library: The library was donated by Mr. Tommy Ilao for the people of Jaén and is located at Barangay Dampulan, beside West Elementary School...already closed....
Pinaglabanan Marker (Lumanas, Sto Tomas South, Jaen, Nueva Ecija): The marker stands where the historical battle between the Spaniards and the people of Jaen took place on September 4, 1896. The group was led by Lt. Col. Delfin Esquivel and they used bolos, spears and several guns. It can be seen now along Sto Tomas South main road (Jaen - Santa Rosa Road) corner Sitio Lumanas (first corner to your right going to Sitio Lumanas if you going to Sto Tomas North)
Resorts:
Villa Aurora Resort (Barangay San Josef)
Golden Shower Resort (Barangay Niyugan)
Tata Guring Mini Resort (Barangay Sto Tomas South)
Province of Nueva Ecija
