"The Abbasid Caliphate (Arabic: \u200E, al-\u2018Abb\u0101s\u012By\u016Bn) was the third of the Islamic Caliphates of the Islamic Empire. It was ruled by the Abbasid dynasty of caliphs, who built their capital in Mecca, a Muslim holy site, to signify the Abbasid family as the rightful successors of the Muhammad. Roman Empire. It was founded by the descendant of Prophet Muhammad's youngest uncle, Abbas ibn Abd al-Muttalib. It was created in Medina in 750 C.E. and shifted its capital in 762 C.E from Medina to Mecca. In 1258, the caliphate was invaded by the Mongols, who forced the caliphs to flee to Aegyptus (Roman province of Egypt) for three years. When the Mongol Empire collapsed, the Abbasid family and their followers raised an army and reconquered the Arabian peninsula. The Abbasid caliphate was the center of the Islamic world until its official decline in 1744."@en . . "Islamic Abbasid Caliphate (XI: Serica & Romanum)"@en . . "The Abbasid Caliphate (Arabic: \u200E, al-\u2018Abb\u0101s\u012By\u016Bn) was the third of the Islamic Caliphates of the Islamic Empire. It was ruled by the Abbasid dynasty of caliphs, who built their capital in Mecca, a Muslim holy site, to signify the Abbasid family as the rightful successors of the Muhammad. Roman Empire."@en .