This research focuses on the historical context pertaining to national security and ethnic relations in northern borders of Thailand and Laos through four important periods, namely:colonization, the Cold War, transition of battlefields into trade wars, and the Chinese influence over the Mekong River sub-region. Furthermore, this article investigates the impacts on national security, as well as security and adaptation of ethnic groups in border areas. The research methodology was based on documentary and field research. The research results revealed that, firstly, since the Cold War era up to the present time, the Thai state has placed significant importance on human security and national security with a focus on state sovereignty over economic security. Secondly, under the context of national security, the more the state expands its power to border areas, the more human insecurity of the ethnic groups becomes evident; especially during the Cold War and the border trade with neighboring countries, where national security agencies have more power than those agencies accountable for economic and border administration. Thirdly, the ethnic groups in border areas have attempted to adapt to difficult circumstances by protecting themselves through various means and by utilizing existing networks and local relationships. Finally, the opening of borders for regional and transnational trade has not led to economic security of those ethnic groups or local small investors who reside along the borderlines. This, however, has provided economic benefits to the state and external investors with large capital and those with better access to opportunities.