Before the Spanish exploration and conquest of what was to become the Philippines, most of the people of the islands lived in barangays, communities named after the boats in which their ancestors are said to have sailed from across the seas. Although such communities were, individually or in groups, self-governing, with no archipelago-wide central authority to which they owed allegiance, they shared similar cultures, customs, languages and traditions, and groups of them were often bound together by family ties or common interests or both.

The centuries-long process of consolidating the islands and seas of the Philippines into a national community and eventually a national state did not begin until Spanish explorers and conquistadores arrived in the sixteenth century. This process was accompanied — and reinforced — by the steady development of a sense of nationhood among the Filipinos themselves.

In May 1493, in an attempt to put some order into the scramble for territories between the two leading maritime powers at the time, Spain and Portugal, the Spanish-born Pope Alexander VI issued a Bull granting to the Spanish sovereigns, Ferdinand and Isabela, “all islands and mainlands found and to be found, discovered and to be discovered towards the west and south” of a line drawn from the North Pole to the South Pole 100 leagues from the Azores and Cape Verde islands (off West Africa) except for lands under Christian possession as of Christmas 1492. (The marriage of Ferdinand and Isabela in 1469 had brought together the kingdoms of Aragon and Castille, forming the foundation of present-day Spain.)

In June 1494, the Spanish sovereigns and the Portuguese King concluded the Treaty of Tordesillas, confirmed by Pope Julius II in 1506, which moved the demarcation line westwards to 370 leagues west of the Azores and Cape Verde islands. Portugal and Spain had initiated the age of European exploration and colonization of the Americas, Africa, the coasts of South Asia, and island Southeast Asia, to be followed by the Dutch and the British. In 1542, Charles V, Holy Roman Emperor and ruler of the Spanish realms, whose maternal grandparents were Ferdinand and Isabela, decided to colonize what was to become the Philippines.