Tl;dr? Student? Teacher? Fairly new to Thailand? You don't want this book. You need David K Wyatt's Thailand: A Short History. Which is longer and more thorough than this mess. Wyatt even covers the origin and range of Tai people if you're curious about the Shan, Tai Daeng, Lao, Tai Lu and their relatives. Genuine footnotes and bibliography too. Follow that with Thailand: Buddhist Kingdom as Modern Nation State by Charles Keyes and The King Never Smiles by Paul Handley.