Explain why terra nullius was an obstacle to achieving native title

The doctrine of Terra Nullius is an expression meaning 'land belonging to no one'. It is used in international law to describe a territory or state which has never been subject to the sovereignty of any state. Despite the criteria needed for the term 'Terra Nullius' to be withstanding, the Europeans still claimed Australia as 'empty land', as they could not see any signs of ownership. Therefore, Terra Nullius became an obstacle in achieving Native Title as for the Aboriginals to prove that that they were the traditional owners of the land, they needed proof that they had maintained an ongoing spiritual and cultural connection with it.