Volume IV of the History of the Caliphate outlines the events of 695-750. This was the period of the highest external power of a single Muslim state, pushing its borders to Southern Gaul, Fergana and the Indus Valley, but gradually losing internal unity under pressure from opposition movements - Shiite, Kharijite and Abbasid. The upper limit of this period was determined by the uprising of Abbasid supporters who replaced the Umayyad dynasty.