The history of Oceania includes the history of Australia, Easter Island, Fiji, Hawaii, New Zealand, Papua New Guinea, Western New Guinea and other Pacific island nations.

The prehistory of Oceania is divided into the prehistory of each of its major areas: Australia, Melanesia, Micronesia, and Polynesia, and these vary greatly as to when they were first inhabited by humans — from 70,000 years ago (Near Oceania) to 3,000 years ago (Remote Oceania).

Indigenous Australians are the original inhabitants of the Australian continent and nearby islands. Indigenous Australians migrated from Africa to Asia around 70,000 years ago and arrived in Australia around 50,000 years ago. The Torres Strait Islanders are indigenous to the Torres Strait Islands, which are at the northernmost tip of Queensland near Papua New Guinea. The term "Aboriginal" is traditionally applied to only the indigenous inhabitants of mainland Australia and Tasmania, along with some of the adjacent islands, i.e.: the "first peoples". Indigenous Australians is an inclusive term used when referring to both Aboriginal and Torres Strait islanders.

The earliest definite human remains found to date are that of Mungo Man, which have been dated at about 40,000 years old, but the time of arrival of the ancestors of Indigenous Australians is a matter of debate among researchers, with estimates dating back as far as 125,000 years ago. There is great diversity among different Indigenous communities and societies in Australia, each with its own unique mixture of cultures, customs and languages. In present-day Australia these groups are further divided into local communities.

The first settlers of Australia, New Guinea, and the large islands just to the east arrived between 50,000 and 30,000 years ago, when Neanderthals still roamed Europe. The original inhabitants of the group of islands now named Melanesia were likely the ancestors of the present-day Papuan-speaking people. Migrating from Southeast Asia, they appear to have occupied these islands as far east as the main islands in the Solomon Islands (archipelago), including Makira and possibly the smaller islands farther to the east.

Particularly along the north coast of New Guinea and in the islands north and east of New Guinea, the Austronesian peoples, who had migrated into the area somewhat more than 3,000 years ago, came into contact with these pre-existing populations of Papuan-speaking peoples. In the late 20th century, some academics proposed a long period of interaction that led to numerous complex changes in the peoples' genetics, languages, and cultures. Kayser, et al. proposed that, from this area, a very small group of people (speaking an Austronesian language) departed to the east to become the forebears of the Polynesian people.

However, the theory is contradicted by the findings of a genetic study published by Temple University in 2008; based on genome scans and evaluation of more than 800 genetic markers among a wide variety of Pacific peoples, it found that neither Polynesians nor Micronesians have much genetic relation to Melanesians. Both groups are strongly related genetically to East Asians, particularly Taiwanese aborigines. It appeared that, having developed their sailing outrigger canoes, the Polynesian ancestors migrated from East Asia, moved through the Melanesian area quickly on their way, and kept going to eastern areas, where they settled. They left little genetic evidence in Melanesia.

The study found a high rate of genetic differentiation and diversity among the groups living within the Melanesian islands, with the peoples distinguished by island, language, topography, and geography among the islands. Such diversity developed over their tens of thousands of years of settlement before the Polynesian ancestors ever arrived at the islands. For instance, populations developed differently in coastal areas, as opposed to those in more isolated mountainous valleys.