The black stump is not so much a signpost, it is a state of mind!
Black stump, as used in the Australian expression 'this side of the Black Stump', suggests a remote place, but not entirely cut off from civilisation. If you are 'beyond the black stump', you are completely isolated.
The expression may have originated as a reference to a tree stump that marked the junction of two stock routes near Merriwagga. This small town lies on the main road between Griffith and Hillston in New South Wales, more than 650km inland. However, there are many other localities in Australia that claim to have the original 'black stump'. A local hotel in Merriwagga claims to be the original Black Stump, but alot of people disagree with this.