This is a link to an interesting site about Australian Aboriginal English .

This page of the site examines a different way of using language - for example, in many varieties of Aboriginal English, questions are often not used to seek important information. People use more indirect ways of finding things out, using hinting or triggering statements. Silence is also important to many Aboriginal interactions, and unlike the use of silence in many Western interactions, it is not seen to be an indication that communication has broken down.

My brother is a linguist and has studied a couple of Aboriginal languages in Western Australia. he told me that one dialect has some Portuguese words in it, and that linguists consider there may have been a shipwreck at some time before European settlement, and that the sailors stayed and integrated with the locals, bringing some of their words into the language.