Thailand has long been perceived by outsiders as an ethnically homogenous country. This is not by accident. It reflects a purposeful government program of nation-building that began in the early 1900s to counter threats from encroaching imperial powers. Understanding that shared ethnicity was the basis of European territorial principles, the Siamese government, for example, ceased referring to the peoples of Lanna and the Khorat Plateau as Lao, giving them instead regional designations: Northern Thai and Northeastern Thai, respectively. This was the official narrative of the Thai nation for decades, and it was centered firmly on nation, religion, and monarchy, which meant: a homogenous ethnically Thai nation speaking a unified Thai language (Central Thai); the Buddhist religion with a new, highly centralized sangha (order of monks); and the Siamese monarchy, with the royal families of the newly incorporated regions gradually being phased out. The nationalist project came under stress as Thailand underwent rapid economic development in the second half of the 20th century. With greater financial security, Thais increasingly valued self-expression, [...]