Geography is the primary organising principle of meaning in Australian Indigenous histories, meaning that it is quite possible for figures from different times to connect with one another as if they were contemporaries. In his Histories, Herodotus delimited the military and political history of the Greeks in part by discrimination from barbarian 'others', and thus established the link between world history writing and actual and desired world order. The growth of intellectual, economic and socio-political networks of exchange in the paleolithic and agrarian eras prompted the defence, augmentation and revision of universal and later world historical views. From the eighteenth century, existing ideas about universal history came to be seen as increasingly out of step with the specialised national research that accompanied the professionalisation of history teaching, research and writing. A more optimistic assessment of 'modern' or 'Western' civilisation was also offered in the works of modernisation scholars. Postcolonial scholars also adapted dependency and world system theory.