It is located in Dibang Valley district and is a sacred heritage of the Idu Mishmis. It is a symbol of past glory and indicate the high standard of civilisation that once prevailed around Bhismaknagar. Bhismaknagar must have been a strong hold of the Chutiyas 12th-16th centuries but the excavations has been throwing new light on its much earlier antiquities. Bhismaknagar stands for what is best in the tribal and Aryans way of life.It speaks for the Catholic spirit of the ancient Indians and the contribution made by the Idus to the synthetic fabric of Indian culture. Today Bhismaknagar has become the nucleus of a renaisance a determination of a sturdy race to revive its traditional culture, while accepting everything that is progressive.