Armed Filipino men are challenging the Malaysian government's power over the province, claiming that this land belongs to the Sultan of Sulu who lives in the Philippines.
"We have achieved something tremendous in our quest for peace in our homeland as well as of course enhancing the freedom of our people. We had to fight for it and in fact we have lost hundreds of thousands of lives just to be able to reach this point. The problem is that our homeland is so rich, not only in terms of history but [also] in terms of its resources, that's why so many people want to occupy this land. And they applied what they call the classical policy of divide and rule so that our people could not unite and fight as one nation to roll back all of these foreign aggressors."
- Nur Misuari, chairman of the Moro National Liberation Front
But the implications here could be severe for the region.
At stake could be the peace deal between the government of the Philippines and the Moro Islamic Liberation Front's (MILF) leader Ibrahim Murad. The deal was designed to bring peace to Mindanao and allow the fighters there to build a semi-autonomous Islamic state, to be called Bangsamoro.
The party that brokered the deal was Malaysia. Its Muslim-dominated government used its influence with the Islamic fighters in Mindanao to bring the parties together. But now, there are allegations that members of the Moro National Liberation Front (MNLF), the original Islamic insurgency group, feels sidetracked and has allowed some of its men to fight the Malaysian government presence in Sabah.
Which brings us back to where the conflict in Mindanao started - it is in places like this that the resistance against what they call Philippine colonialism was nursed.
The fighters would hide in the Muslim ghettos with sympathisers and in turn bring soldiers into the alleyways hungry for revenge. Every family speaks of those years with an overriding sense of loss.
The man who started it all back in the 1970s was Nur Misuari. With international backing he negotiated a separate deal with the government in the 1990s, but he never managed to reach the success MILF reached after splitting with his group.
Today, when we caught up with him in his home in Mindanao, we found a man who is clearly not happy with the current state of affairs. Talk to Al Jazeera speaks to Nur Misuari, the chairman of the MNLF about the crisis in Sabah and peace in the southern Philippines.