New Zealand is a country of islands in the South Pacific Ocean, southeast of Australia. The Maori, the original settlers, are thought to have arrived on the islands one thousand years ago. In 1840, the United Kingdom established British sovereignty through the Treaty of Waitangi signed that year with Maori chiefs, and in the same year British companies began to send settlers to the islands. Subsequent battles between British settlers and Maori ended with the Maori defeat in 1872. In 1907, New Zealand became a self-governing dominion of Britain, but formal independence was achieved 40 years later in 1947. New Zealand is one of the smallest OECD economies. Its economy has traditionally been based on agriculture, but manufacturing and services are becoming increasingly important sectors. With a diverse landscape, tourism has overtaken agriculture as the main source of foreign exchange.