In the aftermath of the First World War, a new route developed between Damascus and Baghdad through the Syrian Desert, driven by the development of motorised transport services and the increasing movement of people, goods and mail between the two cities. This transdesert route linked regions of the former Ottoman Empire that witnessed the formation of separate territorial states in the interwar period. It also connected French and British zones of influence. This dissertation explores the interactions between mobility, space and states in the post-Ottoman Middle East by presenting a history of the Baghdad-Damascus route in the 1920s and 1930s. It first explores the development of this route from 1923 onwards, examining preexisting forms of transdesert mobility, the development of a new transport system and its impact on mobility. In doing so, it shows that the route was shaped by multiple human, technological and environmental factors. The dissertation demonstrates that transdesert mobility accelerated, intensified and diversified, but that these trends did not unfold evenly and consistently. The movements of people, goods and commodities were subject to significant obstacles, dangers and restrictions.The dissertation then investigates how the development of the Baghdad-Damascus route generated interactions between actors having convergent and divergent interests. It shows that the route became an arena of conflict, compromise and cooperation where local, national, international and imperial actors intersected. Finally, the dissertation examines the impact of transdesert mobility on the spatial and territorial reconfiguration of the regions bordering the Syrian Desert. It argues that transdesert mobility played a major role in the formation and consolidation of the states of Iraq and Syria and their border, while contributing to the emergence of a regional space transcending borders, as well as to the integration of this Syrian-Iraqi space into transregional mobility networks.There are many people to whom I am grateful for supporting me during my doctoral studies, and making this research project a truly collective endeavour and experience. First and foremost, I would like to thank my research supervisors. This project would not have been possible without the support and encouragement from Jordi Tejel, who has been there ever since I started thinking about it. Jordi, thank you so much for your guidance and helpful comments on every draft of my work. Our discussions have always taken me one step further towards my goal. I am also very grateful to you for always keeping your office door open (literally) to respond to my most humble questions and assuage my biggest doubts. This journey could also not have been possible without the guidance of Sylvia Chiffoleau, who agreed to become my second supervisor. Her invaluable advice, encouragement and suggestions provide for new avenues of research. I feel deeply indebted to your insightful feedback on my writing, Sylvia, which often made me understand what I had intended t...