Ibn Khaladoun (1332-1406) is considered as the founder of the modern day discipline of social science and history. In his writings he took account of economic, sociological and demographical factors.
The golden age of Islam according to some authors started in the 8th century and ended in the 13th century (750-1258) . In actuality the golden age started with the onset of Islam in the 7th century and ended with the onset of the colonial period and occupation. The Mongol invasion dealt a severe blow to the Muslim regions east of Egypt but they did not slip into dark age. Soon after the death and destruction inflicted by the Mongols, revival took place and scholars like Ibn Khaladoun and others emerged and progress in science, architecture, art, and in every other field continued and ended with the the onset of the colonial period and the European occupation.
The Mongol invasion brought an end to the Abbasid Caliphate in the 13th century and soon after the leadership was taken over by the Ottoman empire. Khaliq
Here is a link to a discussion on Ibn Khaladoun on a program called In Our Times on BBC Radio4. The second link is an interview with Dr. Charles Butterworth of Maryland University on Ibn Khaladoun