The book of G. Gibb was based on the manuscript "Continuation of the Damascus Chronicle" by Ibn-Kalanisi, which became one of the primary sources for the works of all subsequent Arab historians. The author managed, having literary processed the chronicle, to preserve the sequence and reliability of historical events. The materials presented in the manuscript are taken from written and oral sources, sometimes the stories of direct participants in the events are given. That is why the book is unique and of interest to both specialists and a wide range of readers.