The Western Plateau (sometimes referred to as the Australian Shield), is Australia's largest drainage division and is composed predominantly of the remains of the ancient rock shield of Gondwana. It covers two thirds of the continent; 2,700,000 square kilometres of arid land including large parts of Western Australia, South Australia, and the Northern Territory. For comparison, it is roughly the same size as the whole of continental Europe from Poland west to Portugal. It is Australia's largest drainage division.