This book contributes to a better understanding about the dynamics of transnational migration and diaspora in Northern Thailand border areas with Myanmar and Laos. Border cities in Southeast Asia are places that have unique characteristics because of rapid development which includes the process of transnational migration and diaspora communities from neighboring countries. Historically, different ethnic groups had migrated in the border areas of mainland Southeast Asian countries and China. Border cities, such as Mae Sai and Chiang Khong, are strategic places for refugees, minority groups, and others from neighboring countries to reside either temporary or permanently.   The infrastructure and economic developments of those two cities in the border areas have not only influenced the formation of those two cities into multicultural societies, but also become more modern cities with various economic activities. Both Mae Sai and Chiang Khong gradually became more densely populated and have transformed into economic and tourist destinations because they have low-price goods, duty free markets, and even casinos. The arrivals of various ethnic groups in different times have formed a multicultural community, which plays a very important role in the development of border cities and surrounding areas. On top of these, the policies on border areas have been more complex considering the transnational movements of people, goods and ideas.