Institutionally, the military has played a major part in Isabela's and Basilan's volatile history, due to the ongoing conflicts borne out of the Moro Secessionist wars of the 1970s, and more recently, by Al Qaeda backed Islamic fundamentalist groups fomenting a running gun-battle with the Philippines' armed forces for more than a decade.

Also exerting great influence in everyday life is the Roman Catholic Church and the Islamic mufti and imams, religious scholars and leaders who exercise a moral ascendancy over their respective groups.

The Yakans, an inland brave tribe, inhabited the Sulu Archipelago together with the indigenous Sama and Bajau before the Malayan Tausug from Sumatra and Borneo gained control of the area starting 300BCE-200BCE.

Local historians attribute this long lost kingdom to modern-day Kumalarang (now reduced to a Barangay) located along the northwestern coast of Basilan island.

Specifically, according to the Collected Statutes of the Ming Dynasty, a report gleaned from the records of Dezhou, Shandong, China (archived and researched in the years 1673, 1788 and 1935): 3 months after the death of Paduka Batara (the Tausug potentate who visited the Chinese Emperor Yongle and died on October 23, 1417), a High Court Mandarin, Zhan Jian, was ordered to sail to Kumalarang (Chinese texts refer to "Kumalalang"), a vassal state of the Sulu Sultanate located on the northwestern coast of Taguima (Basilan Is.).

On May 27, 1421, however, unaccustomed to the cold climate of the preceding winter and due to his advancing age, Lakan Ipentun died in Fujian, China, just as they were about to embark on Chinese junks that would have brought them home.

His funeral was supervised by Yang Shan, administrator of the temples, and was likewise honored by a eulogy sent by the Chinese Emperor which extolled his virtues of "determination and serenity".

The Jesuit missionaries from Zamboanga arrived on the same year that the removal of Sultan Kudarat's base from Lamitan was effected, and established themselves in Pasangen on the island's northwestern coast.

They constructed the first wooden mission and palisade wall near the mouth of the Aguada River and dedicated the Island to St. Ignatius of Loyola, the founder of the Jesuit Order.

Governor Sabiniano Manrique de Lara signed a decree on May 6, 1662, ordering the military evacuation of the fort in Zamboanga, and of other Spanish colonies, including that of Ternate in the spice islands of the Moluccas.

The Spanish garrisons, along with several priests and their chosen local people, evacuated and returned to Fort Cavite to help defend Manila Intramuros from a threatened invasion by Chinese pirate Koxinga, which never happened.

As fate will have it, the Zamboangueño (the forced Settlers from Luzon and Visayas who populated Zamboanga) and Pasangen, Jesuits included, will amazingly endure another 56 years (1662–1718) of isolated existence and proliferation amidst the hostile threat and return of the Moro master seafarers who overtook and destroyed the abandoned fort.

The Zamboangueños who stayed behind, including many of the founding Jesuit priests who vowed to never forsake their thousands of converted subjects and their new-found religious outpost (prized as the southernmost Catholic strongholds in the entire Philippine islands), were by this time already living within the confines of Zamboanga and Pasangen and its people.

The Jesuits, belonging to the aggressive religious expansionists' Society of Jesus, who remained in Zamboanga were historically credited for reconstructing the damaged fort in 1666, three years after the last Spanish soldiers vacated the walled post in 1663.

Hostilities with the Moro natives and Lumad allies resurfaced in the 18th century and this was triggered by the decision which broke beforehand agreements not to build any additional Forts by both parties when in 1718 Gov.

By then, Badar ud-Din, Sultan of Sulu, who was keenly interested in developing commercial ties with Manila and China, approached the Spanish with a proposal of peace.

However, in a series of raids on the islands of Visayas, where the Spanish themselves got manpower and resources for Zamboanga, angry subjects of the Sultan broke the treaty which resulted in the renewal of large-scale hostilities by 1730.

Throughout this brief period, however, Catholic missionaries continued their avid proselytization, converting very hard the clans of Subanen, Samals, Yakans and Tausugs to Catholicism, adding to the growing Visayan populations brought in primarily from Cebu and Panay.

an island which they called Taguime, intent on establishing a network of naval stations to protect French trade in the area, the Spanish governor protested that Basilan had recognized Spain's sovereignty just the year before, in February 1844.

By 1898, Basilan Island was administratively divided into three districts, the Spanish-controlled towns of Isabela and Lamitan, and the Tausug trading outpost in Maluso, which the Sulu Sultanate handed-over to Spain, subsequent to the razing and occupation of Jolo by the Spanish from 1876 up to 1899, formalized by the Treaty of 1878.

However this was contrasted by the Republic of Zamboanga which claimed sovereignty over the whole of Mindanao, which El Presidente Isidoro Midel and Datu Mandi briefly ruled.

One particular clause, which recognized the Moro practice of slavery, also raised eyebrows in Washington, D.C. Bates later admitted that the treaty was merely a stop-gap measure, signed only to buy time until the war in the north was ended and more forces could be brought to bear in the south.

It is during this phase of the operations when American bombing raids completely destroyed Fort Isabela Segunda, which was used by the Japanese as military headquarters, prison and munitions dump, and razed the "Spanish" Naval Hospital.

Anchoring their stubborn defense around Mount Dabo, some 3,900 Japanese troops held off the U.S. 163rd Infantry supported by Filipino soldiers and other local Moro guerrillas.

Sporadic gun-battles, too, broke out within Isabela's poblacion, and pirate raids harried fishing operations as well as passenger ferry traffic between Basilan and Zamboanga.

840 dated December 11, 1975, reducing the number of municipalities to seven in order to render its " territorial portion more complementary to the size of the area and more responsive to pacification, rehabilitation and total development of the province".

The conversion into a province, and the creation of municipalities ensured that Basilan's sparsely populated areas were "given" to Muslim warlords and surrendering MNLF Commanders by Presidential fiat, as a form of bounty or reward for laying down their arms.

The elevation of Isabela to 4th-class city status gave the local government a much-needed boost, efficiently delivered under the Biel administration, revitalized Isabela City, making it an engine of growth for Basilan province even as the hinterlands was wracked by incessant firefights and gun-battles between the military and bandit groups such as the Abu Sayyaf and Moro Islamic Liberation Front (MILF).

Isabela City then came under the short-lived administration of Vice Mayor Rodolfo Y. Tan, who served the remainder of Biel's term, relinquishing his post after having been defeated in the May 2007 local elections.

Based on the Modified Coronas Climate Classification Scheme by the Philippine Atmospheric Geophysical and Astronomical Service Administration (PAGASA), Isabela City is classified under Type III zone, in which there are no pronounced maximum rain periods with short dry season lasting from 1 to 3 months.