You are using an out of date browser. It may not display this or other websites correctly. You should upgrade or use an alternative browser.
alternatehistory.com
No, that isn't a typo.
With a PoD as far back as one needs (although I suppose the emergence of the Rudolf of Habsburg as Duke of Austria and Styria in 1278 will be as good as any), have either Austria or Hungary (preferably Austria-Hungary) establish a permanent colony in Australia.