Simplify the following text for a Grade 9 native English-speaking person.
Original: Declared an Aboriginal Reserve in 1931 , it remains one of the largest Aboriginal Reserves in Australia and is perhaps best known for its isolation , the art of its people , and the strong continuing traditions of its Indigenous inhabitants .
Simplified: Arnhem Land became an Aboriginal Reserve in 1931 . It is still one of the largest Aboriginal Reserves in Australia .