The history of Australia is the history of the area and people of the Commonwealth of Australia with its preceding Indigenous and colonial societies. Aboriginal Australians arrived on the Australian mainland by sea from Maritime Southeast Asia between 40,000 and 70,000 years ago. The artistic, musical and spiritual traditions they established are among the longest surviving such traditions in human history. The first known landing in Australia by Europeans was by Dutch navigator Willem Janszoon in 1606. Later that year, Spanish explorer Luís Vaz de Torres sailed through, and navigated, Torres Strait islands. Twenty-nine other Dutch navigators explored the western and southern coasts in the 17th century, and dubbed the continent New Holland. Macassan trepangers visited Australia's northern coasts after 1720, possibly earlier. Other European explorers followed until, in 1770, Lieutenant James Cook charted the east coast of Australia for Great Britain and returned with accounts favouring colonisation at Botany Bay (now in Sydney), New South Wales. A First Fleet of British ships arrived at Botany Bay in January 1788 to establish a penal colony, the first colony on the Australian mainland. In the century that followed, the British established other colonies on the continent, and European explorers ventured into its interior. Indigenous Australians were greatly weakened and their numbers diminished by introduced diseases and conflict with the colonists during this period. Gold rushes and agricultural industries brought prosperity. Autonomous parliamentary democracies began to be established throughout the six British colonies from the mid-19th century. The colonies voted by referendum to unite in a federation in 1901, and modern Australia came into being. Australia fought on the side of Britain in the two world wars and became a long-standing ally of the United States when threatened by Imperial Japan during World War II. Trade with Asia increased and a post-war immigration programme received more than 6.5 million migrants from every continent. Supported by immigration of people from more than 200 countries since the end of World War II, the population increased to more than 23 million by 2014, and sustains the world's 12th largest national economy.