Empire is an evocative, yet little examined, word. It can mean the domination of vast territories, a Christian world order, a corrupt form of government, or a humanitarian endeavour. Historians relegate the concept of empire to the pre-modern world, identifying the state as the characteristic political form of the modern world. This book examines the range of meanings attributed to the concept of empire in the medieval and early modern world, demonstrating how the concepts of empire and state developed in parallel, not sequentially.