any ideas when Mindanao officially became part of the Philippines? i can't find a date when i was searching for it..

Was it when the philippines was still part of Sabah and Brunei?

i don't know the exact date but based on various history books, the inclusion of Mindanao may have started during the time of the revolution against the Spanish, (there must be a reason why emilio aguinaldo had a flag made with 3 stars for luzon, visayas and mindanao) but in a way, Mindanao being officially administered by the Philippine government happened during the American period during which gradually, independent sultanates and realms were annexed either through war or diplomacy. After that, they named the whole Mindanao as "MORO PROVINCE", and partly supervised by the Bureau of Non-Christian Tribes, a gov't office made by the Americans.

Hope this helps!!

The Spaniards already called it Mindanao during their era and there is even a major military base of the Spaniards the Fort Pilar.

yeah... but what i am saying is the actual inclusion of mindanao in the philippines... during these times, the spanish government only possessed forts like zamboanga and dapitan...

Mindanao in its entirety never became part of the Spanish Philippines. The Sultanates of Maguindanao and Sulu, and various lumad barangay-kingdoms ruled it.

A Republic of Zamboanga existed as an American protectorate from 1899-1903, with elections even supervised by Americans. It was dissolved and merged into surrounding Muslim provinces as the Moro province.

Mindanao officially became part of the Philippines (in its entirety) when the Americans dissolved the Moro Province (which was ruled somewhat as a separate colony from the rest of the Philippines during 1914.

"Philippines" during the Spanish era included Luzon, Visayas, Marianas Islands, Palau, Caroline Islands, and tiny specks in Taiwan, Mindanao, and Moluccas.