In the traditions of the Indigenous Australian peoples, their ancestors were created with the land, at the dawn of what is called the Dreamtime, the Dreaming or Alterjinga.
Science tells it a little differently. The original ancestors of the people now known as the Australian Aboriginals emigrated to Australia at some point between 40,000 and 120,000 years ago, with an increasing amount of evidence supporting the earliest date. Due to the wide variation of dates, it is unclear whether they arrived here after a sea crossing, or via a landbridge now submerged. It is not known where they first set foot in Australia, nor how many separate waves of migration occurred.
What is for certain is that these people dwelt in Australia with little or no contact with the rest of the world (the Macassar fishing fleets being one of the few exceptions), for thousands of years before European settlement in 1788. Whether or not one accepts the Dreamtime legend, there remains an undeniable case for considering them to be the traditional owners of the land, displaced and disenfranchised by European imperialism.