The original patterns of settlement of the Philippine archipelago are of great importance to an understanding of the present situation, since the differences between the various peoples have by no means been eliminated. Their local particularisms are still sufficiently vigorous and their social structures sufficiently solid to survive in spite of the outside influences to which they have been exposed; and some of the minorities are also protected by their remoteness. The history of the Philippines can be divided into 4 distinct phases: Pre-Colonial Period (before 1521); Spanish Period (1521 – 1898); American Period (1898 – 1946); Post Independence Period (1946 up to present)