 The Abbasid Caliphate , supposedly founded by Muhammad 's uncle Abbas in the 8th century , had ruled northeastern Africa , Arabia , and the Near East . Their seat of power for 500 years was Baghdad , a city considered to be the jewel of Islam and one of the largest and most powerful cities in the world . But under attack from the Mongols , the city fell on February 15 , 1258 , a loss often considered in the Muslim world as the single most catastrophic event in the history of Islam , the end of the Islamic Golden Age . The Christian Georgians had been the first to breach the walls , and as described by historian Steven Runciman , " were particularly fierce in their destruction " . When Hulagu conquered the city , the Mongols demolished buildings , burned entire neighborhoods , and massacred nearly 80 @,@ 000 men , women , and children . But at the intervention of Doquz Khatun , the Christian inhabitants were spared . 
