Initially, the Revolution appeared to be an entirely Tagalog affair. The first eight provinces to rise in arms were all in the Tagalog region and its adjacent areas: Bulacan, Nueva Ecija, Tarlac, Pampanga, Manila, Laguna, Cavite, and Batangas. Even among these provinces, fighting was minimal except for Cavite, Bulacan, and, of course, Manila. Most of the principal revolutionary leaders were Tagalogs, and their initial appeal of support was directed towards the Katagalugan or the Tagalog people. This was not surprising since prior to the Revolution, Filipinos did not think of themselves as one homogenous race. Identity was instead linked with regional ethnicity. The Spanish policy of divisiveness aimed at effecting colonial rule promoted and encouraged regional isolation and ethnic distinctions. By the nineteenth century the term "Filipino" referred to the Spanish insulares or those born in the Philippines. The Filipinos in general were loathingly called indios and their identity was rooted on their regional origin or ethnic affiliation: Tagalog, Kapampangan, Cebuano, Ilocano, Ilonggo, etc.

In the first two years of the Revolution, battles raged mainly in the Tagalog provinces. Outside the Katagalugan, responses were varied. Pampanga, which was close to Manila, was uninvolved in the Revolution from September 1896 to the end of 1897, perhaps because the conditions which drove the Tagalogs to rise in arms were not totally similar in Pampanga. For instance, friar estates or church monopoly of landholdings which triggered agrarian unrest in Tagalog areas was not pervasive in Pampanga. Besides apathy, there were those, such as some Albayanos of Bicol, who were even apprehensive of rumors of a "Tagalog rebellion" aimed at ousting the Spaniards and exercising Tagalog hegemony over the non-Tagalog ethnic groups. Historian Leonard Andaya claims that what brought the Revolution to the non-Tagalog areas was Aguinaldo’s policy of encouraging his military officials to return to their home province and mobilize local support. For instance, the Revolution came late in Antique, and it was due to General Leandro Fullon, an Antiqueno principalia general of Aguinaldo, who went to his home province to spread the Revolution. Even after the Revolution spread to the rest of Luzon and the Visayas, there were still suspicions as to the real motives of the Tagalogs. For example, the Iloilo elite changed the name of their provisional revolutionary government and called it the Federal State of the Visayas since they did not want to recognize the supremacy of Aguinaldo and the Tagalogs. They preferred instead a federal arrangement composed of the three main island groups - Luzon, Visayas, and Mindanao.

These reservations and suspicions by non-Tagalogs were somehow reinforced by the initial writings and proclamations of key Tagalog personalities of the Revolution. Bonifacio wrote a revolutionary piece which he entitled "Ang Dapat Mabatid ng mga Tagalog" or "What the Tagalogs Should Know." Aguinaldo, in his memoirs, wrote chapters entitled "The Tagalog Government Begins" and "Long Live the Tagalogs." But in the absence of a general, generic term to collectively refer to the inhabitants of the archipelago, Filipino being a term originally reserved for the Spanish insulares, Tagalog may have appeared to the leaders of the Revolution as a logical substitute because of its indigenous element.