MANILA, Philippines — The southern Philippines once drew small numbers of foreign militants aligned with al-Qaeda or the Islamic State group to train in a secessionist conflict involving minority Muslims in the largely Catholic nation. That backdrop prompted an investigation this week by Australian and Filipino into a recent trip to the southern Philippine region of Mindanao by the father and son accused of gunning down 15 people at Sydney’s Bondi Beach on Sunday. Australian police said the attack was inspired by the Islamic State group and Prime Minister Anthony Albanese said Tuesday the IS link assessment was based on evidence obtained, including “the presence of Islamic State flags in the vehicle that has been seized.” The Bureau of Immigration in Manila said Tuesday that the suspects stayed in the Philippines from Nov. 1 to Nov. 28 with the southern city of Davao as their final destination before flying back to Australia. Philippine National Security Adviser Eduardo Ano told The Associated Press on Wednesday there was an investigation into whether the suspected gunmen trained with Filipino militants, but supporting evidence has not surfaced. “There is no indicator or any information that they underwent training” in Mindanao, Ano said. Here is a look at the details of Islamic militancy in the southern Philippines: Mindanao has a long history of conflict Centuries of colonialism by the Spanish, the United States and Filipino Christian settlers turned Muslims into a minority group in resource-rich Mindanao, the southern third of the archipelago that has seen decades of intermittent but bloody conflicts over land, resources and political power. Since the 1970s, about 150,000 combatants and civilians have died in the southern Philippines while development was stunted in the country’s poorest region. Western and Asian governments feared the tenacious insurgencies could help foster Islamic extremism in Southeast Asia. Among the foreign militants who have sought sanctuary in Mindanao was Umar Patek, an Indonesian and leading member of Jemaah Islamiyah, a network linked to al-Qaeda. He was convicted of helping make explosives used in the 2002 nightclub bombing in Bali, Indonesia, that killed 202 people, mostly foreign tourists including 88 Australians. He was arrested in Pakistan in 2011, according to Philippine security officials. Fierce rebels became administrators The Philippines government and Muslim separatists signed a peace pact in 1996 that allowed thousands of rebels to return to their communities in Mindanao and retain their firearms. A separate peace agreement signed in 2014 provided broader Muslim autonomy in exchange for the gradual deactivation of thousands of fighters. The pact turned some of the fiercest rebel commanders into administrators of a Muslim autonomous region called Bangsamoro. More importantly, it turned the rebel front into guardians against the Islamic State group and its effort to gain a foothold in Mindanao. Insurgency develops offshoot At least four smaller groups broke off from the two largest Muslim rebel fronts that signed peace deals. The groups included the violent Abu Sayyaf, which would be blacklisted as a terror organization by the US and the Philippines for mass kidnappings for ransom, beheadings and deadly bombings. Most Abu Sayyaf commanders, who had pledged allegiance to the Islamic State group, were killed in battle, including a 2017 siege of southern Marawi, a city in Mindanao, by Filipino forces backed by US and Australian surveillance aircraft. Decades of military offensives have considerably weakened Abu Sayyaf and other armed groups and there has been no indication of any presence of foreign militants in the southern Philippines after the last two groups were “neutralized” in 2023, according to a senior Philippine security official and a confidential joint assessment by the military and police early last year that was seen by the AP. Early this month, the Philippine army reported troops killed a suspected bomb maker and leader of Dawlah Islamiyah-Hassan, a group linked to IS, in southern Maguindanao del Sur province. Sidney Jones, a US-based analyst who has studied Islamic militant movements in Southeast Asia, said that given such militant setbacks it was hard to see why the suspected Bondi Beach attackers would want to train in Mindanao. “The level of violence in Mindanao is high, but for the last three years, it’s almost all been linked to elections, clan feuds, or other sources,” Jones said. “If I were a would-be ISIS fighter, the Philippines would not have been my top destination.”