Berthold Spuler, a German historian, orientalist, Turkologist, one of the leading experts on the history of Islam, presents the history of Islamic civilization – the "Age of the Caliphs" as a global phenomenon that goes beyond the doctrines of the Muslim religion, including cultural heritage, to which all Muslim circles have contributed more or less. Shpuler tells about the rise and fall of both the great Umayyad and Abbasid dynasties, as well as the little-known Nasrid, Hafsid and other dynasties. He also draws attention to Spanish Islam, especially emphasizing its identity. The "Mongol Period" is the history of the Mongols and the countries with which they established contacts and entered into conflicts: the Great Mongol Empire (Genghis Khan and his successors), the state of the Ilkhans of Persia, the Mongols in Central Asia, Mamluk Egypt, Timur, India before and after Timur. The author writes about Muslims in Eastern Europe and in Russian territories. His work is orderly, interesting and understandable.