It is unknown exactly when humans settled in Victoria. A site near Keilor has evidence of Australian Aborigines living near on the Maribyrnong River more than 31,000 years ago. Victoria was one of the most populated areas of Australia. The Aborigines used fire-stick farming to burn the volcanic plains regularly, and they became some of the biggest grass plains in the world. This supported large numbers of animals such as kangaroos and wallabies. The Kulin federation were a large language group that lived on the plains and included the Watha wurrung, Boon wurrung, Woi wurrung, Daung wurrung and Djadja wurrung people. Other groups in Victoria included the Jari Jari, Ladji Ladji, Wemba Wemba, Wergaia, Jardwadjali, Gunnai, Waywurru and the Taungurung. In the rivers, creeks and wetlands the Aboriginals had built large fish traps to catch both fish and eels. In the Yarra River wetlands, some of these traps had stone walls about high.