How could an empire stretching from the Hindukush to the Atlantic be governed for about 300 years, from ca. 650 to the 950s? How far did the geographic, political, economic, and linguistic reach of the Islamic Empire extend within and beyond the societies that it governed? Based on case studies on various regions inside and outside the empire proper, the authors pursue these questions by challenging the perception of an empire entailing the military and administrative control over these vast regions. They investigate the reach of Arabic as the imperial language, Sunni Islam as the imperial religion, and the reaction of communities that resisted religious integration, such as Muslim Ibāḍīs, or the Zoroastrians. The Empire’s reach into the provinces is largely a question of negotiation between these provinces and the center. It integrates societies and is limited by local rebellion. Emphasis is given to Daylam, Ṭabaristān, the Jazīra, and to the economic integration of regions beyond political control. ‘The Reach of the Empire’ sheds light on the complex ways of the functioning of the early Islamic Empire. It underlines its various layers of government, its impacts on different communities and their place within the empire.