The Australian Antarctic Territory (AAT) is a part of Antarctica. It was claimed by the United Kingdom and placed under the authority of the Commonwealth of Australia in 1933. It is the largest territory of Antarctica claimed by any nation. In 1961, the Antarctic Treaty came into force. Article 4 deals with territorial claims, and although it does not renounce or diminish any preexisting claims to sovereignty, it also does not prejudice the position of Contracting Parties in their recognition or non-recognition of territorial sovereignty. As a result, only four other states recognise Australia's claim to sovereignty in Antarctica. 

AAT consists of all the islands and territory south of 60°S and between 45°E and 160°E, except for Adélie Land (136°E to 142°E), which divides the territory into Western AAT (the larger portion) and Eastern AAT. It is bounded by Queen Maud Land in the West and by Ross Dependency in the East. The area is estimated at 5,896,500 km. 

The territory is inhabited by the staff of research stations. The Australian Antarctic Division administers the area primarily by maintaining three year-round stations (Mawson, Davis and Casey), which support various research projects. 

The territory is divided into nine districts, which are from West to East: These regions are split into two separate areas geographically, with George V Land and Oates Land lying to the east of the French Territorial claim of Adélie Land, and all other districts lying to its west.
Since when have they claimed it?
1933