Aboriginal Australians arrived on the Australian mainland between 40,000-60,000 years ago. The first known European landing was by Dutch navigator Willem Janszoon in 1606. Britain established a penal colony in New South Wales in 1788. Over the following century, British colonists established other colonies and explored the interior, bringing disease and conflict with Indigenous groups. Australia federated as a nation in 1901, and its population grew significantly in the 20th century through immigration and economic development.