Minority Muslim groups in the southern Philippines - known collectively as the Moros - have been fighting for self-determination for nearly 40 years.

The Mindanao region remains a melting pot of breakaway rebel groups, pan-Asian militant Islamist groups and communist rebels rubbing shoulders with mercenary kidnap groups and clan militias.

As a result, regular eruptions of violence have forced hundreds of thousands of residents from their homes. Many return fairly quickly, only to be displaced again. In total, the various conflicts in Mindanao have displaced up to 2 million people since 1970.

Together, the Moro and communist insurgencies - two of the world's longest-running conflicts - have killed at least 160,000 people.

Muslims arrived in the Philippines in the 13th century. Mindanao, the southernmost of the country's three regions, was ruled by sultanates well before Spanish Christians arrived in the second half of the 16th century.

This historical perspective drives the long-standing grievances of many Filipino Muslims (part of the Bangsamoro ethnic group) who want to re-establish a Muslim homeland.

When the Philippines passed from Spanish to American control at the end of the Spanish-American War in 1898, large areas of the Muslim south remained untouched.

A process of economic and political integration followed in the first decades of the 20th century, accelerating when the Philippines won independence in 1946. In the years that followed, the government encouraged Catholic settlers to move from the north to resource-rich Mindanao, displacing the comparatively poorer Muslim communities.

By the late 1960s, campaigners were demanding recognition of Moro rights, angered by their increasing marginalisation. They argued that the influx of Christians had by this time reduced their presence to some 5 percent of the population.

Moro National Liberation Front
In 1972, a university professor called Nur Misuari reformed the Muslim advocacy group he headed as an armed rebel organisation, naming it the Moro National Liberation Front (MNLF). Its stated aim was to fight oppression and create an independent Muslim state in the south.

Communal conflict erupted shortly afterwards when Philippines President Ferdinand Marcos declared martial law in response to the insurgency.

In the years that followed, the MNLF took control of large areas of Mindanao and the neighbouring Sulu archipelago.

The MNLF agreed to a peace accord with the government in 1976, but fighting resumed after a failed referendum in the southern islands. A comprehensive peace agreement was not signed until 1996, under the presidency of Fidel Ramos.

The deal did not grant independence to the south, but led to the creation of the Autonomous Region of Muslim Mindanao (ARMM), comprising the mainland provinces of Maguindanao and Lanao del Sur, and the island provinces of Sulu, Tawi-Tawi and Basilan.

Misuari was elected governor of the ARMM, but his administration was widely criticised for incompetence and corruption. The ceasefire collapsed in 2001, when MNLF guerrillas loyal to him attacked an army base in Jolo, Sulu, killing 100 people and wounding scores.

The rebel leader fled to Malaysia, saying the attacks were justified because the government had reneged on the peace deal and abandoned southern regions to poverty. He was promptly captured and jailed for the attack.

Although many senior former rebels now work within the ARMM structure, widespread disaffection persists among MNLF leaders who argue that the government is still failing to promote economic development in the south.

Despite its continuing influence, the MNLF has weakened and fractured over the years, giving rise to several splinter groups.

Moro Islamic Liberation Front
The failed 1976 accord led to a partial break-up of the MNLF membership. The group's second-in-command, Salamat Hashim, went on to found the Moro Islamic Liberation Front (MILF).

Although its aim of a fully independent state differed little from that of the MNLF, the group was more militant and put greater emphasis on traditional and scholarly interpretations of Islam.

By 1996 - the year full peace was agreed with the MNLF - Hashim had amassed more than 12,000 MILF fighters in camps in Mindanao. Peace negotiations with the government got under way in 1997, and a ceasefire was agreed.

The truce collapsed in 2000, when then President Joseph Estrada declared war on the MILF and overran 47 of its Mindanao camps, leading to fighting that displaced nearly 1 million people.

The ceasefire was re-established in 2001 when Estrada's successor, Gloria Macapagal-Arroyo, came to power, but broke down yet again when government troops overran the MILF's headquarters in Buliok, Maguindanao. Up to half a million people were displaced.

Another ceasefire was agreed in July 2003. But negotiations stalled in 2006 because of differences over the size of the proposed ancestral homeland and the proportion of natural resources that should be allocated to its people.

After more than 10 years of stop-start talks the government agreed a deal with the MILF in 2008, which would expand the existing Muslim region and give its future government wide political and economic powers. But the Supreme Court halted the signing ceremony after Catholic politicians in the south said they hadn't been consulted.

The situation on the ground deteriorated rapidly. Disgruntled MILF field commanders attacked villages, prompting troops to launch an offensive that displaced hundreds of thousands of people.

Manila called an end to peace talks with the MILF in September 2008 after deciding to scrap the deal altogether.

At the end of 2008 the Philippines said it was rebuilding a peace panel with a view to resuming talks with the MILF.

The upsurge in fighting since August has killed more than 300 people and displaced 700,000, according to media reports.

Abu Sayyaf Group
The Abu Sayyaf Group (ASG) - which translates as "Bearer of the Sword" - was formed in 1990-91 by MNLF members angered by Misuari's perceived moves towards a peaceful resolution of the conflict. Along with its desire to create an independent Islamic nation in the Philippines, the group has broader visions of a pan-Islamic super-state in southeast Asia.

Based in Mindanao, Abu Sayyaf began with small attacks but soon graduated to large assaults as well as the kidnapping and murder of foreigners. The group's first large-scale action was a raid on the town of Ipil in Mindanao in April 1995. In 1997, the U.S. State Department designated ASG as a "Foreign Terrorist Organisation".

In 2000, an ASG faction abducted 21 people, including 10 Western tourists, from a resort in Malaysia. A year later, the ASG kidnapped three U.S. citizens and 17 Filipinos from a resort in Palawan in the Philippines. Several, including a U.S. citizen, were murdered. Two further hostages were killed during a Philippine military rescue operation.

Philippine authorities say the ASG was behind a 2002 bombing near a Philippine military base in Zamboanga that killed a U.S. serviceman. In 2004, an ASG faction bombed SuperFerry 14 in Manila Bay, killing more than 130 people.

According to the U.S.-based National Memorial Institute for the Prevention of Terrorism, the group largely finances itself through ransom and extortion.

In March 2004, Philippine authorities arrested an ASG cell whose bombing targets included the U.S. Embassy in Manila.

Philippine and U.S. authorities say Abu Sayyaf has links with international terrorist organisations such as al-Qaeda and the radical Indonesian group Laskar Jihad. It is also suspected of ties with the regional militant network Jemaah Islamiah, believed to have been behind the 2002 Bali bombings, which killed more than 200 people.

Members of such groups are thought to have gone into hiding among Mindanao's myriad waterways and islands. Analysts say Indonesian militants belonging to Jemaah Islamiah have travelled virtually unchecked between Indonesia and the Philippines, using Mindanao as a training base and refuge. Some Indonesian militants believed to be on Jolo are wanted in connection with the Bali bombings.

In August 2006 local officials said they had found a stockpile of bombs at an Abu Sayyaf hideout in Jolo that were very similar to bombs made by an engineer working in Indonesia for Jemaah Islamiah.

Since August 2006 thousands of troops have been trying to flush the rebels out of Jolo. In early 2007, the army announced it had killed senior Abu Sayyaf figure, Abu Sulaiman, and that tests on a body found in December confirmed the death of the group's chief, Khaddafy Janjalani, who had a $5 million U.S. bounty on his head.

But analysts say that even if the military could maintain its momentum against Abu Sayyaf, Manila needs to use softer tactics to fully root out the causes of Muslim militancy in the south.

Because of traditional kinship and loyalty ties, many MNLF and MILF members maintain links with Abu Sayyaf. Ethnic and blood relations often transcend membership of any particular group.

With this in mind, Philippine and U.S. planners are now trying to use "soft power" to win over local residents and deny the rebels a place to hide. Their plan, which they say is based on a successful turnaround on neighbouring Basilan, includes development, reform of the security forces, and political empowerment of disenfranchised Muslims.

Aside from the long-running conflict between the government and the Muslim minority in the south, some 40,000 people have been killed in a 40-year communist rebellion across the Philippines.

The New People's Army (NPA) - active in 69 of the country's 81 provinces - was formed in 1969 as the military wing of the outlawed Communist Party of the Philippines, Marxist-Leninist (CPP-ML).

The revolutionary Maoist group grew to number some 25,000 fighters in the mid-1980s, driven by a radical anti-U.S. and communist agenda, with the aim of liberating the working masses by overthrowing the government and redistributing wealth.

In 1992, the Philippine Congress repealed the 1957 Republic Act that had outlawed the CPP.

The NPA weakened amid purges towards the end of the 1990s. Current numbers are unclear but media reports put the figure at about 5,000.

The United States designated the NPA as a "Foreign Terrorist Organisation" in 2002. The group's founder, Jose Maria Sison, lives in exile in the Netherlands.

The NPA's primary tactic is prolonged guerrilla warfare, combined with intimidation of foreign investors, extortion and targeted assassination of Filipino citizens who oppose the group.

NPA rebels are strong in the poor, typhoon-prone eastern part of the archipelago, from Cagayan valley in the northern Luzon area down to Quezon and Bicol regions in southern Luzon, as well as Samar and Leyte islands in the central Philippines and the Surigao and Agusan areas on Mindanao.

Confrontations between the armed forces and the NPA periodically displace thousands of people.

Peace talks, brokered by Norway, stalled in 2004 when Manila refused to help persuade the United States and some Western European states to remove the NPA from terrorism blacklists.

The army has seen a rise in NPA attacks in mining and logging areas on Mindanao since August 2008 when the government stepped up its fight against Muslim rebels in the same region.

Communist rebels have also blown up cellular phone sites.

There is increasing concern about the use of child soldiers in Mindanao. According to a 2004 report by the Coalition to Stop the Use of Child Soldiers, testimonies by former NPA members revealed "massive recruitment" of children aged 13 to 17.

While the NPA denies this, it is thought that a quarter of new recruits are children, representing some 3 percent of regular troop strength. Their tasks range from regular combat to post-battle scavenging.

The report quoted government estimates that 10 to 15 percent of MILF members and 15 to 30 percent of Abu Sayyaf members were under 18.

Since the Sept. 11, 2001 attacks in the United States, Arroyo has been one of Asia's most vocal backers of U.S. President George W. Bush's global "war on terror". In return, she has received significant U.S. military support for her campaign against militants in Mindanao.

Washington insists that U.S. troops are only present in the Philippines in a training and advisory capacity - they closed their last base in the country in 1992. But reports of a leaked Pentagon document in 2003 pointed to a private agreement between the two governments, allowing U.S. special forces to engage in direct operations against Islamist groups on Basilan island.

Left-wing groups were outraged, given that the Philippine constitution forbids foreign troops from fighting on its soil.

In 2006, the United States and the Philippines agreed to forge a new security arrangement, setting up a joint panel called the Security Engagement Board. The accord expands their security cooperation to cover piracy, terrorism, disasters and diseases.

Backed by hundreds of millions of dollars of U.S. funding, the Armed Forces of the Philippines have launched large military crackdowns against Abu Sayyaf and other fugitive militants, employing aerial and artillery attacks.

The raids have caused thousands to flee their homes and have infuriated the MILF and the MNLF. Clashes have occurred between the government and both groups. Fighting with the NPA also continues. Tens of thousands have been temporarily uprooted during clashes and army crackdowns on rebels.

In addition, the presence of the army and so many armed factions often fans the fires of traditional family feuds, leading to clan-based violence on Mindanao. The head of one of the biggest aid donors to the region, the Japan International Cooperation Agency, has said that clan wars are more of a threat to peace than Muslim rebellions. Both the army and rebel groups have been drawn on several occasions into clan confrontations, which have displaced thousands.

Mindanao is also prey to groups known as "lost commands" - former military or insurgent units no longer under the control of their superiors who live off banditry and kidnapping. Two of the most notorious are the Pentagon Gang and Abu Sofia.

According to the U.S. Agency for International Development 2005-2009 Philippines Strategy document, the country faces a daunting range of development challenges: continuing conflict, corruption, a comparatively weak investment climate, inadequate revenue generation, rapid population growth, structural poverty, a deteriorating educational system, environmental degradation, and weaknesses in its institutions of governance.

Some 43 percent of Filipinos live on less than $2 a day, according to the U.N. Development Programme's 2007/2008 Human Development Report. That figure is even higher in Mindanao, where significant numbers of children are stunted, says the World Food Programme.

In areas affected by conflict, particularly on Mindanao, the effects of poverty are compounded by displacement.

Conditions in evacuation centres are poor. Local government units charged with dealing with displaced people lack resources and are dependent on non-governmental organisations and external aid.

Because war and displacement on Mindanao are cyclical, efforts to rehabilitate affected people tend to be unsuccessful. Quite apart from the suffering of displaced people, the broader population in Mindanao remains economically marginalised and lacks adequate access to basic social services.