The Indian state of Arunachal Pradesh has a total population of roughly 1.4 million (as of 2011) on an area of 84,000 km2, amounting to a population density of about 17 pop./km2 (far below the Indian average of 370 pop./km2 but significantly higher than similarly mountainous Ladakh). Much of Arunachal Pradesh is forested. The "indigenous groups" account for about two thirds of population, while immigrants, mostly of Bengali/Hindi belt origin, account for a third. List of tribes The Scheduled Castes and Scheduled Tribes Lists (Modification) Order (1956 and as inserted by Act 69 of 1986) lists twelve tribes of Arunachal Pradesh explicitly, but makes explicit that the list is non-exhaustive by noting that "all tribes of the State, including" those listed are to be considered "Scheduled". There are 26 major tribes and more than 100 sub tribes in Arunachal Pradesh. The twelve tribes listed are: Adi (Abor), Aka, Apatani, Nyishi, Tagin, Galo, Khampti, Mishmi, Momba (Monpa), "any Naga tribes", Sherdukpen, Singpho. By ethnolinguistic classification: Tibeto-Burman Bodic Languages Monpa (Chugpa, Takpa, Tshangla/Memba et al.) Tibetans (Tibetan languages) Khamba Tani Apatani/Tani, Galo/Abor, Nyishi, Hill Miri, Tagin, Na/Nga, Mising/Mishing Adi/Lhoba (Millang, Minyong, Padam Digaro-Mishmi Mishmi (Idu Mishmi, Digaro Mishmi/Taraon/Darang Deng), Miju Miju Mishmi, Zekhring Lolo-Burmese Yobin Hruso (association with Tibeto-Burman doubtful) Hruso/Aka, Miji/Sajolang/Damai Kho-Bwa (association with Tibeto-Burman doubtful) Bugun (Khowa) Sherdukpen/Mey, Sartang Lispha, Chug Sulung/Puroik (association with Kho-Bwa doubtful) Sal languages (Naga tribes [mostly Tibeto-Burman speaking; Nagamese creole], c.f. "Northern Naga") Singpho Tangsa, Nocte, Wancho, Tutsa Southwestern Tai Khamti Khamyang Other Indigenous Assamese people Chakma people(Mix of tibeto burman and indo aryan). Distribution of various ethno-linguistic group in the state As one of the Seven Sister States of eight if including Sikkim in India's remote north-east, it is culturally at least as much part of Southeast Asia as it is of South Asia; ethnolinguistically, it is divided between various Tibeto-Burman speaking Tribes. Monpa area bordering Bhutan to the west, the Tani and Mishmi areas in the center, Singpho/Tangsa/Yobin area bordering Myanmar to the east and the Naga area bordering Nagaland in the south. It shares a large part of its border with China and the Indian state of Assam. In between there are transition zones, such as the Bugun/Aka/Hruso/Miji/Sherdukpen area, which form cultural "buffers" between the Tibetic Buddhist tribes and the Tani hill tribes. In addition, there are isolated peoples scattered throughout the state. Within each of these cultural spheres, one finds populations