The Philippine archipelago is believed to have been formed at least 30,000 years ago when migrants from the Indonesian archipelago and elsewhere settled in. Additional migrations took place over the next millennia. Over time, social and political outfits developed and evolved in the widely scattered islands. The first settlers in the Philippines crossed seas and bridges from mainland Asia to arrive in this group of islands, and they were the Negritos. Several thousand years later, Austronesian settlers travelled the same route as the Negritos - but this time over sea in their impressive boats.