Task: Question Generation
Input (English): After the Marzpanate period (428–636), Armenia emerged as the Emirate of Armenia, an autonomous principality within the Arabic Empire, reuniting Armenian lands previously taken by the Byzantine Empire as well. The principality was ruled by the Prince of Armenia, and recognized 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 center in the Armenian city, Dvin. The Principality of Armenia lasted until 884, when it regained its independence from the weakened Arab Empire under King Ashot I Bagratuni.
Output (English): When did the Principality of Armenia end?