After the Sasanian period (428–636), Armenia emerged as Arminiya, an autonomous principality under the Umayyad Caliphate, reuniting Armenian lands previously taken by the Byzantine Empire as well. The principality was ruled by the Prince of Armenia, and recognised by the Caliph and the Byzantine Emperor. It was part of the administrative division/emirate ''Arminiya'' created by the Arabs, which also included parts of Georgia and Caucasian Albania, and had its centre in the Armenian city, Dvin. Arminiya lasted until 884, when it regained its independence from the weakened Abbasid Caliphate under Ashot I of Armenia.