Some of the Lau Islands to the southeast of Fiji have strong historic and cultural links with Tonga.
However, in essence, Polynesia is a cultural term referring to one of the three parts of Oceania (the others being Micronesia and Melanesia).
New Zealand, Norfolk Island, and Ouvéa, the Polynesian outlier near New Caledonia, are the unsubmerged portions of the largely sunken continent of Zealandia.
Zealandia is believed to have mostly sunk 23 million years ago and recently resurfaced geologically due to a change in the movements of the Pacific Plate in relation to the Indo-Australian plate, which served to uplift the New Zealand portion.
The results of research at the Teouma Lapita site (Efate Island, Vanuatu) and the Talasiu Lapita site (near Nuku'alofa, Tonga) published in 2016 supports the Express Train model; although with the qualification that the migration bypassed New Guinea and Island Melanesia.The oldest rocks in the region are found in New Zealand and are believed to be about 510 million years old.The oldest Polynesian rocks outside of Zealandia are to be found in the Hawaiian Emperor Seamount Chain and are 80 million years old.Polynesia is generally defined as the islands within the Polynesian Triangle, although there are some islands that are inhabited by Polynesian people situated outside the Polynesian Triangle.Geographically, the Polynesian Triangle is drawn by connecting the points of Hawaii, New Zealand and Easter Island.