This book, which I have previously announced under the title ‘The Roman Origins of Islamic Clientage’, has its roots in a chapter of my thesis, ‘The Mawālī in the Umayyad Period’, London Ph.D. 1974. (Of the entire thesis it may now be said that in so far as it has not been published, it has been abrogated.) Though the roots are now exceedingly long, I should like to thank Professor B. Lewis for reading the first draft of what was in due course to become this book without reacting so negatively as to kill the idea, for all that it was undoubtedly the most chaotic piece that I have ever written. Michael Cook not only went through the same ordeal, but also read and commented on numerous subsequent drafts and suggested that I add what is now Chapter 2. I should also like to thank the Islamicists at the Hebrew University of Jerusalem for extracts from their concordance of Arabic poetry, Professor S. Moreh for help with the translation of poetry, Professor F. de Jong for help with rare publications, David Powers for making me think about bequests again, Fritz Zimmermann for comments on the first chapter, and Martin Hinds for comments on the entire final draft.