While the first sign of magic within the Filipino thousands of years ago hasn't been pinpointed quite yet, it is true that the Autonomous Region of Magical Philippines has risen together with the great Kingdom of Namayan. The ARMP had no name in the past since it was one with Namayan.
For years, the Magicals and the Muggles lived in harmony, no prejudice and no discrimination. Of course, there were some groups that wanted the Magicals to separate from the Muggles but they were scarce and were merely a small nuisance. The Magicals helped the Muggles in more difficult work and the Muggles gave the Magicals a sense of purpose. They all thought it would last forever and nothing could disrupt the peace. Until the Spaniards came.
The Spaniards didn't like the idea of people using magic and strove hard to separate the 'normal' from the 'abnormal'. People possessing magic or showing that they possessed magic were hunted down and were executed. Some were smart enough to hide their magical abilities while the others fled to remote areas and islands. The Muggles helped the ones who hid their abilities to hide and kept the location of the remote areas and islands from the Spaniards.
Years passed by, and the Muggles slowly forgot about their friendship and alliance with the Magicals due to little to no contact. The newer generations were taught that Magic was evil and was abnormal which lead to the Magicals completely separating from the Muggles. While the Muggles were under Spain, the Magicals thrived and grew, watching helplessly as the Muggles were tortured colonial master after colonial master. As a way of coping with the loss of their friendship, the ARMP mirrored the cultural progression of Muggle Philippines, albeit with their own magical touches.
They still kept the monarchy intact. However, they had changed the surname to del Castillo and had turned into a patriarchy, which didn't please most of the citizens.
Several centuries and generations later, the ARMP has become an isolated region, its government keeping to itself and lying low as possible while making its economy flourish. It's been known to most of the Wizarding World as a very shady government and some trying to get information on it are rebuffed every single time. They don't join international events even if they are qualified and during wars, they stay neutral and keeps their citizens close. Now, the ruling monarch is King Alejandro with his wife, Queen Marisol. The current heir to the throne is Prince Martin. Several of the Noble Houses has grown bigger while others have grown smaller or extinct. Some members of the Noble House of Iglesias and Fernandez has moved to the United Kingdom, still under the protection of the Crown. Recently, the two royal del Castillo children have moved there in hopes of establishing trading agreements with the British Ministry.
The House of Edillon is the temporary Noble House of MIMAROPA after the Niesa Family Breakdown. Prior to that, they were the second most powerful family in the region, being bodyguards to the Niesas. They were easy to underestimate, seeing as they were a mostly pacifist family. You could call them the Hufflepuffs of the Philippines. Despite the Niesas being neck-deep in Dark Arts, they remained loyal to them. This is because of the pact, sanduguan, made by their ancestors many centuries ago.
After the Niesas were held down by the Crown, the King chose the Edillons to rule over MIMAROPA while the Niesas were given time to sort their problems out.