The Abbasid Caliphate (Arabic: العبّاسيّون‎, al-‘Abbāsīyūn) is an Arab Dynasty of rulers, overthrowing the Ummayad Dynasty. It was built by the descendant of Muhammad's youngest uncle, Abbas ibn Abd al-Muttalib. It was created in Harran in 750 AD. and shifted its capital in 762 AD from Harran to Baghdad. Over the next two hundred years, it would reach its peak before collapsing again to the Fatimids in the West, and Mongols to the East. During the The Caliphate Wars it would make its comeback, making risky moves in order to justify its claim of being the head of world Muslim leadership.