Pampangos and Luzons in Sumatra
Either Colin or his Pampango informant may have remembered the account wrong as they say the people of the lake claimed their ancestors ventured to Pampanga. Indeed, it was Colin's theory that the Kapampangans did originate from Sumatra. However, neither Kapampangan or any language mutually intelligible with Kapampangan is found in Sumatra. Any ancestral connection is unlikely given the different structures and genetic relationships of languages in both regions.
Another explanation is that the inhabitants of the lake came from Pampanga more recently and settled in the area. In turns out that more than a century earlier, people from Lusung (Luzon) were involved in the geopolitics of northern and western Sumatra. Here is a snippet from Mike Pangilinan's article Lusung [呂宋]: A preliminary investigation into its role in East Asian history.
The source for this information is mainly Portuguese texts which refer to people from the kingdom of Luzon as Luções "Luzons." These Luzons, as can be seen by the quote above, were involved in fighting both for the leaders of Aceh in Northern Sumatra and of Menangkebau in Western Sumatra around 1529.
Quite possibly, these Luzons settled in the area after their service. This was not unusual as we also know from Portuguese sources that there were Luzons permanently settled in Malacca, Brunei and other areas at this time. The largest lake on Sumatra is Lake Toba, which is between the Batak-Menanagkebau and the Aceh kingdoms. There are also smaller lakes located quite near the Menangkebau region.
The anonymous document Relación de las Islas Filipinas, which is part of the collection from 1580 to 1605, is dated by Blair and Robertson at about 1586 on internal evidence. In talking about the people of Pampanga, the author says "they are keen traders, and have traded with China for many years, and before the advent of the Spaniards, they sailed to Maluco, Malaca, Hazian, Parani, Brunei and other kingdoms."
"Hazian" has been interpreted my some experts as referring to Aceh in Sumatra. We know from Ming Dynasty maps, that the kingdom of Lusung (Luzon) did not refer to the whole island known today but to the Manila Bay area and particularly to the area north of the Manila Bay, which would correspond to the Pampanga region.
Therefore, it is quite possible that the Pampango-speaking people living in Sumatra in the mid-17th century were descendents of the Luzons who fought for the Menangkebau or the Aceh kingdoms, or both more than a century earlier.