The western Pacific is divided into three anthropological areas: Melanesia; Micronesia and Polynesia.

Here is a useful article on modern thinking about the history of this area.

Melanesia (Islands of Blacks) refers to Papua New Guinea, Solomon Islands, New Caledonia, Fiji and neighboring areas. The peoples of this area were thought to resemble Africans, although genetic evidence shows they are not closely related.
Polynesia (Many Islands) is inhabited by peoples who are believed to have come originally from Taiwan (before the arrival of the Chinese) and South East Asia and spread across the Pacific. Their dispersal may have been from Borneo or Java and then via Samoa, known in their legends as "Havaiki, Birthplace of Lands". Hawaii is named after the place of origin. One of the Borneo branches went west as far as Madagascar and Africa, the eastern branch went in the direction of Hawaii (100 CE), Easter Island - Chile (400) and New Zealand (750). The latest genetic evidence suggests that at least some of them came from Vanuatu (2000 BCE).
Micronesia (Small Islands) is a transition area.
Micronesia = Kiribati (Gilberts) Guam, Nauru, Northern Marianas, Fed. states of Micronesia, (Yap, Pohnpei, Truk, Kosrae Palau (Belau) Marshall islands.

Languages: Austronesian languages in Nauru, Kiribati, Marshalls, etc. are mutually unintelligible, Polynesian languages in Tuvalu (Ellice) and Nukuoro and Kapinga-Marangi have more in common. English is used throughout.

History: Western Micronesia was formerly believed to have been settled from Indonesia or Philippines after 1500 BCE. Estimates are now much earlier (3000 BCE) and it is now believed that the different societies evolved in the area. The languages however show signs of common origin across the area from Madagascar in the west to Easter Island and Hawaii in the east.
(Modern genetic analysis shows that Easter Islanders came from the west (400 CE), that is they are Polynesians. There is no evidence that they came from South America. The Kon Tiki expedition only showed that a raft could have carried people in that direction, not that it did. If a few people did travel, it would have been culture they carried, not genes. (Moreover, it is now believed the ancient Incas did not possess the sails which Heyerdahl used and so could not have made the voyage.)
Eastern Micronesia was probably settled from Melanesia much earlier (2000 BCE).

European Contacts
The whole area came under European influence from the 17th century. Spaniards arrived in 1668. The British, French and Dutch naval forces and commerical ships visited the area. Britain, France, Spain and Germany made colonies in the area. Spain's islands went to Germany, then Japan and finally to the US.

Thor Heyerdahl - Kon Tiki
Heyerdahl proved that a balsa wood raft could make the journey from Peru to Polynesia, but did not establish that there were real connections between the two cultural areas. Genetic analysis has not provided evidence of contact.
Thor Heyerdahl - Kon Tiki



Kon-Tiki: Ein Floß treibt Über den Pazifik

See Kon Tiki