An Austronesian-speaking group linked to the archeological construct known as the Lapita cultural complex reached and colonized Tonga around 1500–1000 BCE. The dates of the initial settlement of Tonga are still subject to debate. Nevertheless, reaching the Tongan islands (without Western navigational tools and techniques) was a remarkable feat accomplished by the Lapita peoples. Not much is known about Tonga before European contact because of the lack of a writing system during prehistoric times other than the oral history told to the Europeans and the Eurocentric interpretations of Polynesian culture by Europeans. The first time the Tongan people encountered Europeans was in 1616 when the Dutch vessel Eendracht made a short visit to the islands to trade. By the 12th century Tongans, and the Tongan paramount chief, the Tuʻi, had a reputation across the central Pacific, from Niue to Tikopia, leading some historians to speak of a 'Tongan Empire'. In the 15th century and again in the 17th, civil war erupted. It was in this context that the first European explorers arrived, beginning with Dutch explorers Willem Schouten and Jacob Le Maire in 1616, who called on the northern island of Niuatoputapu, and Abel Tasman, who visited Tongatapu and Haʻapai in 1643. Later noteworthy European visits were by Captain Cook (British Navy) in 1773, 1774, and 1777, Alessandro Malaspina (Spanish Navy) in 1793, the first London missionaries in 1797, and the Wesleyan Methodist Walter Lawry Buller in 1822.
In 1845 the ambitious young warrior, strategist, and orator Tāufaʻāhau united Tonga into a kingdom. He held the chiefly title of Tuʻi Kanokupolu, but was baptised with the name King George. In 1875, with the help of missionary Shirley Waldemar Baker, he declared Tonga a constitutional monarchy, formally adopted the western royal style, emancipated the 'serfs', enshrined a code of law, land tenure, and freedom of the press, and limited the power of the chiefs.
Tonga became a protected state under a Treaty of Friendship on 18 May 1900, when European settlers and rival Tongan chiefs tried to oust the second king. Within the British Empire, which posted no higher permanent representative on Tonga than a British Consul (1901-1970), it was part of the British Western Pacific Territories (under a colonial High Commissioner, then residing on Fiji) from 1901 until 1952. Although under the protection of Britain, Tonga is the only Pacific nation never to have given up its monarchical government as did Tahiti and Hawaiʻi. The Tongan monarchy unlike the UK follows a straight line of rulers.
The Treaty of Friendship and Tonga's protectorate status ended in 1970 under arrangements established by Queen Salote Tupou III prior to her death in 1965. Tonga joined the Commonwealth of Nations in 1970 (atypically as an autochthonous monarchy, that is one with its own hereditary monarch rather than Elizabeth II), and the United Nations in September 1999. While exposed to colonial forces, Tonga has never lost indigenous governance, a fact that makes Tonga unique in the Pacific and gives Tongans much pride, as well as confidence in their monarchical system. As part of cost cutting measures across the British Foreign Service, the British Government closed the British High Commission in Nukuʻalofa in March 2006, transferring representation of British interests in Tonga to the UK High Commissioner in Fiji. The last resident British High Commissioner was Paul Nessling.