Before the 1500s, at least three linguistic families had established themselves in Oceania: Australian languages in the Australian continent and Tasmania, Austronesian languages in Micronesia and Polynesia, and both Austronesian and non-Austronesian languages in New Guinea and Melanesia. Whether the non-Austronesian languages represent one (huge, diverse, ancient) family is a focus of scholarly debate.
Of these families, the Austronesian is the newcomer. Possibly more than five...