His seven-volume Universal History is a monumental study of world civilization in his time as seen from an Arab viewpoint.
Historians consider it one of the major historical works of the Middle Ages.
Ibn Khaldun believed civilizations rise and fall in constant cycles. Hard work and cooperation bring wealth and luxury. But then selfishness, corruption, and decline set in. He expressed his theories in Muqaddima, the first volume of Universal History. Ibn Khaldun described his experiences as a politician and statesman in his Autobiography.