Short answers, pulled from the story.
Ibn Khaldun was an Arab scholar, historian, philosopher, and sociologist who lived from 1332 to 1406. He is widely acknowledged as one of the greatest social scientists of the Middle Ages and is considered a major forerunner of historiography, sociology, economics, and demography.
The Muqaddimah, or Prolegomena, is Ibn Khaldun's best-known book and the introduction to his planned history of the world. It is built around his concept of asabiyyah, or group solidarity, and argues that a society's high point as a great civilization is followed by a period of decay before a more vigorous group conquers it.
Ibn Khaldun was born in Tunis in 1332, into an upper-class family of Arab descent that traced its ancestry to Hadhramaut in the southern Arabian Peninsula. His family had emigrated to Tunisia after the fall of Seville to the Reconquista in 1248.
Ibn Khaldun met Timur, the founder of the Timurid Empire, during the siege of Damascus in 1400. He remained at the besieged city for seven weeks and was lowered over the wall by ropes to negotiate, in meetings where Timur questioned him about the lands of the Maghreb.
Ibn Khaldun outlined early theories of the division of labor, taxes, scarcity, and economic growth, and is argued to have originated the labor theory of value before Adam Smith and David Ricardo. In 1981, U.S. President Ronald Reagan cited him as an influence on his supply-side economic policies.
Ibn Khaldun spent his later years in Cairo teaching and serving as a judge, being called six times to the office of Maliki qadi. He died on the 17th of March 1406, one month after his sixth selection to that office, having been placed under arrest amid suspicion of joining an underground reform party.