Karachi, Pakistan’s largest city and economic hub, has been touted as ‘the most dangerous megacity in the world’. Rampant urban violence, ethnic strife and the outbreak of terror activities post-9/11 have created insecurity and instability in the city, which some scholars argue has paved the way for migrations to the Gulf coast, as well as Europe, in search of economic and social security. These out-migrations, however, are not just a result of current violence and instability. They stem from a longer history that dates back to Karachi’s infrastructural development as a port city -- the labour used in the construction of the harbor were migrants from the Iranian side of the Makran coast and Oman. This paper shows that this historical mobility and movement of people opens the port city into an oceanic frontier, unhinging territorial fixities and creating renewed regional formations. Examining visual, scholarly and literary material on Karachi, I argue that the city deterritorializes itself from a South Asian frontier through ongoing labour migrations as well as movement of objects, images and ideas across the Persian Gulf. It loosens ties of cultural rootedness in various forms, such as nostalgia for an unrealized Western modernity vis-a-vis Karachi’s colonial past, and current movements of people towards the Middle East in search of economic security. To borrow from Kamran Asdar Ali, the efficacy of the category of the city lies within its urban spatiality, whereby gendered, raced and classed subjects negotiate the terms of belonging while being the objects of urban projects. I argue, however, that this efficacy also creates an excess, whereby the material infrastructure and historical particularity of Karachi as a port city allows it to remain in an ongoing territorial flux, and thus evade geographical fixities and recalibrate regional boundaries.