when was tasmania cut off from the mainland
Tasmania The island is believed to have been occupied by Aboriginals for 40,000 years before British colonisation. It is thought Tasmanian Aboriginals were separated from the mainland Aboriginal groups about 10,000 years ago when the sea rose to form Bass Strait.[17] The Aboriginal population was 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 1100 Aboriginals and settlers. The near-destruction of Tasmania's Aboriginal population has been described by some historians as an act of genocide by the British.