Millenarianism among hilltribes in Southeast Asia stems from various factors, such as cultural meanings of these ethnic groups, their economic and political status from the late 19th to the 20th centuries, influences of mainstream cultures, and influences of Christian missionaries. Cultural meaning is a special way of practices for a better new world. Certain aspects of the meaning are shared among hilltribes in Thailand because their mentalities and worldviews about cosmology are fundamentally similar. Hilltribes are traditionally deemed “losers”, but their legends provide them with hope that their golden age will be returned in the present world. Ethnic cultures are facing and are threatened by mainstream cultures, so Christianity provides them with an alternative. Christianity and ethnic beliefs are coincidentally similar, particularly with regard to Doomsday. The development of such a relationship between the two cultures has created cultural innovations. Hill cultures, being minority ethnic groups and the influences of Christianity have created unexpected political movements as well as a redefinition of their ethnicities, e.g., the Karen Liberation Army. However, the life of the ethnic groups has been changed in many respects. Television is in place of oral tales and ready-made clothes are worn instead of traditional home-spun dress. Nevertheless, educated hill people are aware of their ethnic identities and issues on economic and political equality.