The book is a publication of the Master thesis of orientalist, Arabist, historian of Byzantium A. A. Vasiliev. He analyzes Byzantine-Arabic relations in the time of the Amorian Dynasty, from 820 till 867; there was also its sequel on the Macedonian Dynasty, from 867 till 959. First of all, he speaks about political relations, but also some issues of inner structure of Byzantium and Arabic Caliphate, culture of both states, and their mutual influence. The work consists of two parts. The first one is about the events in 820-867; there are three chapters in it: chapter 1: about Emperor Michael II, chapter 2: about Emperor Theophilos, chapter 3: about Emperor Michael III. The second part includes supplements: compositions by Arabic historians: Ibn Koteyba, Belasori, Yakubi, Tabari, Masudi, Riyad an-Nuthus, Ibn Miskaveykha, Ibn al-Asyra, Ibn Adari, Nuveyri et al.; and texts by later Arabic authors based on European data. Another supplement is on the embassy of John VII Grammatikos to Bagdad. The third supplement is called ‘Restoration of Orthodoxy’ and gives information on the period of the triumph of Orthodoxy. So, after analyzing the new data, he established that it happened on March 11, 843 – not the February 19, 842. In the fourth supplement there is ‘On chronology of Patriarchs of Constantinople from 815 till 867’, where the data was checked carefully. In the fifth supplement ‘The chronology of the Byzantine-Arabic relations at the Amoriam Dynasty’ from December 25, 820 – the start of the reign of Michael II, till September 24, 867 – the death of Michael III.