A number of methods of acquisition of sovereignty are or have been recognised by international law as lawful methods by which a state may acquire sovereignty over territory. International law adopts much of Roman property law in regards to acquisition of sovereignty due to the underlying European civil law at the time of early discovery voyages such as Christopher Columbus.[1] The basis of acquisition of states ownership of vacant territory therefore continues to apply, (and was often applied historically to land already possessed by indigenous populations).[2]