In a land area of 43, 955 square kilometers, the diocesan territory covers civil districts of Changlang, Upper Dibang Valley, Lower Dibang Valley, Anjaw, Lohit and Tirap in the state of Arunachal Pradesh.
Arunachal Pradesh is situated in the north-east corner of India. It is called 'the land of the rising sun' and is the habitat of 26 Mongoloid tribes and their sub tribes scattered over an area of 87,400 square kilometers. This land borders China, Tibet, Bhutan and Myanmar and comprises snow-capped mountains of the Himalayas and flooding river valleys.
502,000 is the total population in the diocese. Tangsa, Lisu or Yobin, Singpho, Tutsa, Chakma, Adibasis, Ponthais Idu Mishmi, Idu, Adi, Mishing, Mishmis. Zakhring, Deori, Khamti, Mishmi, Singpho, Wancho, Lazu, Tutsa are the various ethnic groups in the diocesan territory.
The villages and small towns are administered by elected local bodies called panchayats and municipalities, respectively.
The nearest airport is Dibrugarh which is 150 kilometers away.
The per capita income in the diocesan territory is Rs 25, 836 ($550) as of October 2009. Farming is the main occupation, done by 90 percent the population. Petroleum and coal mining industries are also situated in the diocese.
Government and private operators provide extensive telecommunication facilities in the diocesan area. The diocese is well connected by local cable TV networks.
Nearly 54.34 percent is the literacy rate in the diocesan territory.