The Ottoman Empire’s territorial and maritime reach throughout its nearly 600-year existence led to a plethora of adversaries at whose expense the empire continued to expand. The resulting boundaries that constantly shifted over time prove to be sites of cultural, socioeconomic, as well as political history. Ottoman borders are critical windows into the dynamics shaping the larger empire, including the great urban centers often located far from these frontiers. The territorial limits (or beginnings) of this multiethnic empire, extending from South Arabia, the Persian Gulf, and Libya, to the Danube and the Caucasus, are crucial tools to gain insights into the complexities that constitute the processes by which the Ottomans administered as much as lived in these regions. Be they witness to the stability that accompanied peace between neighboring states or the frequent volatility caused by war, the empire’s edges served as theaters for intraimperial development that shaped subject and state alike.