The island is believed to have been occupied by indigenous peoples for 30,000 years before British colonisation. It is thought Aboriginal Tasmanians were separated from the mainland Aboriginal groups about 10,000 years ago when the sea rose to form Bass Strait. The Aboriginal population is estimated to have been between 3,000 and 7,000 at the time of colonisation, but was almost wiped out within 30 years by a combination of violent guerrilla conflict with settlers known as the "Black War", intertribal conflict, and from the late 1820s, the spread of infectious diseases to which they had no immunity. The conflict, which peaked between 1825 and 1831, and led to more than three years of martial law, cost the lives of almost 1,100 Aboriginals and settlers.
The state is named after DutchexplorerAbel Tasman, who made the first reported European sighting of the island on 24 November 1642. Tasman named the island Anthony van Diemen's Land after his sponsor Anthony van Diemen, the Governor of the Dutch East Indies. The name was later shortened to Van Diemen's Land by the British. It was officially renamed Tasmania in honour of its first European discoverer on 1 January 1856.
Tasmania was sometimes referred to as "Dervon," as mentioned in the Jerilderie Letter written by the notorious Australian bushrangerNed Kelly in 1879. The colloquial expression for the state is "Tassie". Tasmania is also colloquially shortened to "Tas," mainly when used in business names and website addresses. TAS is also the Australia Post abbreviation for the state.