There the matter rested for over 100 years, and it was not until 1917 that researchers realised that the "forester kangaroo" of Tasmania was in fact "Macropus giganteus", the same western grey kangaroo that was, and still is, widespread in the more fertile south-eastern part of the mainland. By 1971, it was understood that the Kangaroo Island species was the same as the kangaroos of southern Western Australia, and that this population extended through much of the eastern part of the continent as well. For a time, three subspecies were described, two on the mainland and one on Kangaroo Island. Finally, by the early 1990s, the current understanding emerged.