Tasmania (/tæzˈmeɪniə/; abbreviated as TAS, nicknamed Tassie) is an island state of Australia. It is located 240 km (150 mi) to the south of the Australian mainland, separated by Bass Strait. The state encompasses the main island of Tasmania, the 26th-largest island in the world, and the surrounding 334 islands. The state has a population of around 533,308 as of March 2019[update]. Just over forty percent of the population resides in the Greater Hobart precinct, which forms the metropolitan area of the state capital and largest city, Hobart. Tasmania's area is 68,401 km2 (26,410 sq mi), of which the main island covers 64,519 km2 (24,911 sq mi). It is promoted as a natural state, and protected areas of Tasmania cover about 42% of its land area, which includes national parks and World Heritage Sites. Tasmania was the founding place of the first environmental political party in the world. 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 island was permanently settled by Europeans in 1803 as a penal settlement of the British Empire to prevent claims to the land by the First French Empire during the Napoleonic Wars. The island was initially part of the Colony of New South Wales but became a separate, self-governing colony under the name Van Diemen's Land (named after Anthony van Diemen) in 1825. Approximately 75,000 convicts were sent to Van Diemen's Land before transportation ceased in 1853. In 1854 the present Constitution of Tasmania was passed, and the following year the colony received permission to change its name to Tasmania. In 1901 it became a state through the process of the Federation of Australia.