During the next week, the Mongols sacked Baghdad, committing numerous atrocities; there is debate among historians about the level of destruction of library books and the Abbasids' vast libraries. The Mongols executed Al-Musta'sim and massacred many residents of the city, which was left greatly depopulated. The siege is considered to mark the end of the Islamic Golden Age, during which the caliphs had extended their rule from the Iberian Peninsula to Sindh, and which was also marked by many cultural achievements in diverse fields.