which Whadjuk people were involved. Lieutenant George Grey took great efforts to learn the Whadjuk tongue, and was recognised by the Yellagonga's Whadjuk group as being the returned dead son (i.e. Djanga) of an Aboriginal woman, before going on to a distinguished political career in South Australia and New Zealand. European settlers were initially called Djanga – a term referring to spirits of the dead – by the Whadjuk. This belief incorporated Europeans into the social structure of the Noongar peoples and was reinforced by several factors. To the Whadjuk, the settlers resembled dead people because they: came from the west, the direction of the setting sun and Kuranyup, the land of the dead for the Whadjuk; were pale in complexion – which was seen by the Whadjuk as the pallor of people after death; often changed their clothing and, therefore, their general appearance; smelled bad and often had rotten teeth, reflecting early 19th century standards of hygiene and; were not affected by infectious diseases to which most Aboriginal people had no genetic resistance. Work by Neville Green in his book Broken Spears has shown how Aboriginal culture could not explain the high death rates associated with European infections, and believed that Aboriginal sorcery was involved, leading to rising numbers of reprisal spearing and killings within the Aboriginal community. Coupled with the declining birth rates, these factors led to a collapsing population in those areas nearby European settlement. In addition to white killings and massacres in Fremantle and elsewhere, the arrival of Europeans saw many deaths from diseases to which Aboriginal people had no resistance. These were interpreted as sorcery within traditional culture and led to "pay-back" vendettas, which increased mortality of those in closest contact with Europeans. Aboriginal camping sites around Perth Goonininup, now built over by the present day Swan Brewery, together with the nearby site of Goodinup, marked the place where coastal and inland Nyungar met for trade and ritual purposes. It was a focal point for trading in red ochre. Male initiations also took place there. Close by was Koyamulyup (frog camp), so-called because of the abundance of frogs, an important part of the local diet. The Boya (or birthing stone) there was pushed into the river by European settlers to try to prevent Aborigines accessing the site. Lake Monger was an Aboriginal camping site until the 1920s. When it was closed the land was used