Where did the Greater Central Philippine Languages (GCP) originate from?
The Greater Central Philippine Languages (GCP) includes the Central Philippine Languages (CP), South Mangyan, Palawanic, Subanen, Danao, Manobo, and Gorontalo-Mongondow subgroups. Within CP alone there is the subgroups of Tagalog (or Kasiguranin-Tagalog), Bikol, Visayan, and Mansakan. Many of you know that the Bikol, Visayan, and Mansakan subgroups have several languages underneath them. The GCP is a very large group in terms of the number of total languages and number of speakers which may account for at least 75-80% of the Philippines' total population. It also has extensive sub branching. Some have proposed that the GCP or CP languages originate in Northern Mindanao or neighboring Southern Visayas, and this may be true. But there are a few issues that have to be explained away.
A 2021 population genetic study "12 Important Insights into the Genetic Origins and Diversity of the Filipino People" showed that people all over Mindanao including Northern Mindanao have significant Manobo ancestry, and this Manobo ancestry is also significant among the Waray (who represent Eastern Visayas), Cebuanos and Boholanos (representing Central Visayas) all of whom speak languages within the Visayan subgroup. But this Manobo ancestry is absent in Western Visayas such as among the Hiligaynons, Kinaray-as (or Karay-as), the Suludnon (Panay Bukidnon), the Panay Ati, and also among the Bukidnon groups of Negros Island (Magahat and Karolanos people?) and Negros Ati. The Manobo ancestry is also absent among the Tagalogs, Bicolanos, the various Agtas groups of the Bicol Peninsula, and the various groups of Mangyans in Mindoro Island. All these groups speak a CP language except for the Northern Mangyans who speak non-GCP languages, but the Southern Mangyans do speak a CP language. The Tausug who now reside in the Sulu Archipelago are a Visayan speaking group and are linguistically closely related to the Butuanon speakers of Northeastern Mindanao (and also to the Surigaonons and Tandaganons of that same region) also do not possess any Manobo ancestry. The Tausugs are thought to have migrated from Northeastern Mindanao to the Sulu Archipelago. So if the GCP or CP language group originated in Mindanao or Southern Visayas, why wasn't the Manobo ancestry carried outside these regions where many (if not the majority) of the GCP or CP speakers now reside?
Furthermore, Austro-Asiatic ancestry is found in the Sulu Archipelago and Zamboanga Peninsula (Southeastern Mindanao), and also throughout the island of Palawan and the Calamian Islands especially among the non-Tagalog and non-Visayan groups. If the GCP or CP languages originated there, then we would expect to see Austro-Asiatic ancestry found where GCP and CP languages predominantly now reside which is the rest of Mindanao (that is, outside of Southeastern Mindanao), the Visayas, and Southern Luzon, but we don't.
Further complicating this issue is that we have the Maragtas and the Legend of the 10 Datus, and their celebrations such as the Ati-Atihan Festival which state that Western Visayans (the Visayans of Panay Island, western half of Negros Island, Guimaras Island, and nearby speakers such as the Cuyonons, Caluyanons, and Inonhanons) all originate from Northern Borneo. The Ratagnons also speak a Western Visayan language, but much of their ancestry may be an indigenous Mangyan ancestry from Mindoro since they reside there. The Spanish in the past even asked many of the Visayans where they originate from, and they said Poni (or Kingdom of Poni or Boni) from Northern Borneo.
However today, Northern Borneo (or Borneo in general) doesn't have much GCP speakers except maybe for the Tausug or Suluk speakers, and a few Iranun speakers all of whom reside in the Sabah state of Malaysia of Northeastern Borneo. As mentioned earlier, the Tausugs are thought to originate in Northeastern Mindanao as they are linguistically closely related to the Butuanon speakers. The Iranuns may have migrated into the Sabah region of Northern Borneo from Mindanao sometime in the 1800s. The Gorontalo-Mongondow languages (a GCP subgroup) are all found in Northern Sulawesi, Indonesia.