This article will deal with how the main Islamist thinker have understood and framed issues of borders and sovereignty in their writings. At a time when political Islam is facing major changes in the wake of the Arab uprisings, it is necessary to highlight what they have produced in terms of geopolitical analysis, and more especially when it comes to connections between religious identity, borders, State-building and the wish to reunite all the Muslims under one rule (the Caliphate). In the light of the history of Islamist thought, I intend to shed light on its conception of borders, from the colonial era to the radical turmoil faced by Arab States nowadays. I will concentrate on how this ideological design has been evolving since the rise of political Islam in the 1920s, and to what extent topics such asborders, identity, religious sovereignty and search for the Caliphate are now interpreted by some Islamist a more moderate and flexible way. I will pay specific attention to the main Islamist leaders and thinkers of our time (Rached Ghannouchi, Hassan Tourabi, Abdelilah Benkirane…). I have met some of them and will these interviews to illustrate my points.