The author owes an immense debt of gratitude to the many who have assisted and advised in the research and writing of this book. First and foremost, Professor David Abulafia, my PhD supervisor, guided me with a wonderful combination of scholarly advice, critical analysis, kindness and friendship. Dr. John Edwards and Dr. Alexandra Sapoznik, my PhD examiners, offered many critical comments, invaluable guidance and numerous textual improvements. I am also greatly indebted to Professor Thomas Barton for his time, care and enormous expertise and knowledge in providing numerous comments which have immeasurably improved the final product. Dr. Christopher Briggs has also provided many comments and much support for this book and related publications. Rabbi Chaim Weiner gave me invaluable assistance in interpreting rabbinic responsa. I am also grateful for their advice to Professor Asunción Blasco Martínez and Dr. Anna Rich Abad and to the many staff members at the archives in Barcelona, Girona and Zaragoza, who have been unfailingly courteous and helpful. Above all, I am eternally indebted to my wonderful wife, Sue, and daughters, Hannah, Rachel and Naomi who have both inspired me and tolerated the many hours of research into a subject distant in both geography and chronology. It goes without saying that all errors and omissions remain entirely my own.