The Outback is a remote, vast, sparsely populated area of Australia. The Outback is more remote than the bush. While often envisaged as being arid, the Outback regions extend from the northern to southern Australian coastlines and encompass a number of climatic zones, including tropical and monsoonal climates in northern areas, arid areas in the "red centre" and semi-arid and temperate climates in southerly regions. Geographically, the Outback is unified by a combination of factors, most notably a low human population density, a largely intact natural environment and, in many places, low-intensity land uses, such as pastoralism (livestock grazing) in which production is reliant on the natural environment. The Outback is deeply ingrained in Australian heritage, history and folklore. In Australian art the subject of the Outback has been vogue, particularly in the 1940s. In 2009, as part of the Q150 celebrations, the Queensland Outback was announced as one of the Q150 Icons of Queensland for its role as a "natural attraction". History Aboriginal peoples have lived in the Outback for at least 50,000 years and occupied all Outback regions, including the driest deserts, when Europeans first entered central Australia in the 1800s. Many Aboriginal Australians retain strong physical and cultural links to their traditional country and are legally recognised as the Traditional Owners of large parts of the Outback under Commonwealth Native Title legislation. Early European exploration of inland Australia was sporadic. More focus was on the more accessible and fertile coastal areas. The first party to successfully cross the Blue Mountains just outside Sydney was led by Gregory Blaxland in 1813, 25 years after the colony was established. People, starting with John Oxley in 1817, 1818 and 1821, followed by Charles Sturt in 1829–1830, attempted to follow the westward-flowing rivers to find an "inland sea", but these were found to all flow into the Murray River and Darling River, which turn south. From 1858 onwards, the so-called "Afghan" cameleers and their beasts played an instrumental role in opening up the Outback and helping to build infrastructure. Over the period 1858 to 1861, John McDouall Stuart led six expeditions north from Adelaide, South Australia into the Outback, culminating in successfully reaching the north coast of Australia and returning without the loss of any of the party's members' lives. This contrasts with the ill-fated Burke and Wills expedition in 1860–61 which was much better funded, but resulted in the deaths