The Abbasid period constitutes a significant portion of Muslim history, spanning from the year 231 AH to 656 AH. After that, the Abbasid dynasty continued to rule in Egypt as a caliphate, until the year 329 AH. This dynasty marked a new era in world history; various sciences flourished during this period, making its age truly a “golden age of Islam.” Many great figures emerged from this dynasty, including those from ancient noble families and independent scholars who competed to expand the Islamic territories. Many states were established under the Abbasid rule, but they eventually became weaker due to competition from other states like the Ayyubids in Morocco, the Fatimids in Egypt, or the neighboring Romans. This book provides a detailed account of the political situation of the Abbasids, from the beginning of their caliphate in Khurasan and Iraq, to its end under the Mongol rule of Hulagu Khan.