Spanish–Moro conflict
The Spanish initiated the conflict by conquering the Philippines and invading Moro territory in an effort to subjugate the region to their rule since the 1500s. When the Spanish conquered the Muslim Kingdom of Maynila, a vassal of the Sultanate of Brunei, the Islamic rajah, Rajah Sulayman resisted the Spanish. Manila then became the capital of the Spanish Philippines after the conquest, with the Spanish forcibly converting people to Catholicism. The Spanish–Moro Wars started with the Castille War, a war between Spaniards and the Sultanate of Brunei. (The term "Moro" at this time included Muslim Tagalogs who were ruled by the Sultanate of Brunei).
Mindoro
The island was briefly invaded by the Sultanate of Brunei and housed Moro settlements before the Spanish invaded and Christianized the population. Afterwards, the area was depopulated due to wars between the Spaniards and the Moros from Mindanao who sought to enslave the hispanized people and to re-islamize the island. Consequently, most of the population fled to nearby Batangas and the once rich towns of Mindoro fell to ruin. In the seventeenth century, Giovanni Francesco Gemelli Careri visited the island.
In 1898, Mindoro joined in the Philippine Revolution against Spain due to the influx of rebels settling into the island from Cavite and Bataan. Local patriotism died down however during the American occupation of the Philippines and the Japanese era.