https://www.britannica.com/place/Melanesia
Melanesian culture, the beliefs and practices of the indigenous peoples of the ethnogeographic group of Pacific Islands known as Melanesia. From northwest to southeast, the islands form an arc that begins with New Guinea (the western half of which is called Papua and is part of Indonesia, and the eastern half of which comprises the independent country of Papua New Guinea) and continues through the Solomon Islands, Vanuatu (formerly New Hebrides), New Caledonia, Fiji, and numerous smaller islands. The Andesite Line, a geological feature of extreme volcanic and earthquake activity, separates Melanesia from Polynesia in the east and from Micronesia in the north, along the Equator; in the south, Melanesia is bounded by the Tropic of Capricorn and Australia. Melanesia’s name was derived from the Greek melas ‘black’ and nesoi ‘islands’ because of the dark skin of its inhabitants. In the early 21st century the population of Melanesia was approximately 10 million.
Although the prehistory of most of island Melanesia has not been fully documented, evidence suggests that the cultural, linguistic, and political fragmentation that prevailed at the time of European arrival, with a half-dozen languages and cultures often represented on a single island, was partly a product of transformation that had occurred during the previous 2,000 years. Hierarchical political systems and associated trade networks seem to have broken down during this period and appear to have been accompanied by the increasing separation of language or dialect groups. The causes of these transformations, perhaps including internecine warfare and the spread of diseases (malaria in particular), remain unclear. These changes were accelerated by European arrival, which further disrupted trade systems, intensified intercommunity warfare by supplying firearms, thinned populations by introducing diseases and indentured labour, and eroded traditional authority systems.
Europeans first exerted colonial influence in Melanesia in 1660, when the Dutch announced sovereignty over New Guinea in an effort to keep other countries from encroaching on the eastern end of the profitable Dutch East Indies (now Indonesia). Over the next several centuries Britain, the Netherlands, Australia, Germany, and Japan each established colonial claims to various parts of Melanesia. Colonial disruptions continued throughout the 20th century and into the 21st.