Okinawan Karate - A History of Styles and Masters - Vol 1 - Shuri-te and Shorin-ryu by Christopher Clarke
For an eye-opening view of our karate heritage, this book is recommended, full of stories of the great masters and styles and some valuable insights into the truths behind some of the myths of martial arts.
Okinawan Karate - A History of Styles and Masters - Vol 2 - Fujian Antecedents, Naha-te, Gojo-ryu and Other Styles by Christopher Clarke
This volume continues the information trail and is also recommended.