Why did the Abbasids move the capital of the caliphate to Baghdad?

The Abbasid caliphs moved their capital to Baghdad in 762 CE primarily because they required a central base for their empire that was more strategically and logistically advantageous than their previous locations in Kūfah or the remote region of Khorāsān.1

The selection of the site by the caliph al-Manṣūr was considered an act of genius for several reasons:

• Strategic Location: The city was situated with access to both the Tigris and Euphrates river systems, facilitating efficient transport and trade. It was also positioned near the primary route through the Zagros Mountains toward the Iranian plateau, allowing for better control over the eastern provinces.1
• Economic Viability: The location allowed for the easy transport of agricultural goods, such as wheat and barley from Al-Jazīrah and dates and rice from Basra, supporting the growth of a massive population.1
• Administrative Consolidation: By establishing a dedicated government quarter—the "Round City"—the Abbasids could centralize their authority, eventually transforming Baghdad into a premier commercial and intellectual hub of the Muslim world.12