Ibn Khaldun was born in Tunis in 1332 and died in Cairo in 1406. He is the most significant social scientist of Classical Islam, whose work has preserved its message and timeliness until our times. The society he ingeniously described has remained familiar to the posterity due to the survival of several elements of patrimonial empire in the Middle East. The up-to-date character of his work is also assured by the fact that he is being considered as the "founding father" of almost half a dozen disciplines. His unique work, al-Muqaddima (Introduction to History) first formulated in 1375, has won the great esteem of later centuries because of two remarkable achievements. One of them is that he, laying the foundations of his pioneer and deeply original theory of civilisation, made history a never-before-existing independent discipline. His other great scientific achievement is the model-like elaboration of (patrimonial) empires, which has preserved its validity even until today in the examination of the formations of the Eurasian steppe zone. The monograph analyses these two great scientific accomplishments in detail. The author has been studying Ibn Khaldun and his oeuvre for more than 25 years. A thoroughly commented translation of the al-Muqaddima, which was an indispensable pre-work to this book, was published in Hungarian in 1995.