This paper investigates the conservative reflex to arrest the fluidities of identity and to retard the exchanges of ideas, blood and language that inevitably followed in Southern Africa over the first half of the 20th century through border-regulation. This first half of this paper is a basic legal and policy overview, but I highlight how migration law was made unstable through a ‘politics of exemption’. The second half illustrates how the fences around the South African state were imagined, bent and seized by those other than the politicians, legislators and technocrats. Much of the literature on statebuilding and nationalism focuses on the making of boundaries. This paper also focuses on their consequent ‘unmaking’. From the start South Africa’s migration policy – in so far as there was a policy - was implicated in, even founded upon, sustained negotiations with non-bureaucratic practice. These contingencies meant that the borders were in reality little more than lines in the sand; yet in the imagination, the foundations sank deep.