The study of the movements of people has been an important dimension of anthropological discourse that offered a unique opportunity for anthropologists to study centre-periphery relations and to gain new insights into population movements produced by regional and global political, economic, and historical processes. A range of factors are associated with the internal migration of tribal people in Arunachal Pradesh from their ancestral habitations that is hills, to the foothills. This paper aims to find out the factors responsible for migration of the tribals. The study has been conducted in Papum Pare district of Arunachal Pradesh on the people migrated from Kurung Kumey district. The major finding of the study is that tribal people are to a great extent migrated to foothills voluntarily for economic reason. It also indicates that among tribal communities living in the capital region of Arunachal Pradesh, mainly Nyishi people have been migrated in large number. It finds that youth are clearly ahead of their counterparts in migrating to the foothills. The traditional culture and customs of the migrants are significantly affected after their migration which has been highlighted in the present paper.