Northeast India constitutes a single linguistic region within the Indian national context, with about 220 languages in multiple language families (Indo-European, Sino-Tibetan, Kra–Dai, Austroasiatic, as well as some creole languages) that share a number of features that set them apart from most other areas of the Indian subcontinent (such as alveolar consonants rather than the more typical dental/retroflex distinction). Assamese, an Indo-Aryan language spoken mostly in the Brahmaputra Valley, developed as a "lingua franca" for many speech communities. Assamese-based pidgin/creoles have developed in Nagaland (Nagamese) and Arunachal (Nefamese), though their use has been on a decline in recent times. The Austro-Asiatic family is represented by the Khasi, Jaintia and War languages of Meghalaya. A small number of Tai–Kadai languages (Ahom, Tai Phake, Khamti, etc.) are also spoken. Sino-Tibetan is represented by a number of languages that differ significantly from each other, some of which are: Bodo, Rabha, Karbi, Mising, Tiwa, Deori, Biate etc. (Assam); Garo, Hajong, Biate (Meghalaya) Ao, Angami, Sema, Lotha, Konyak etc.(Nagaland); Mizo, Hmar, Chakma etc. (Mizoram); Hrusso, Tanee, Nisi, Adi, Abor, Nocte, Apatani, Misimi etc. (Arunachal). Meitei is the official language in Manipur, the dominant language of the Imphal Valley; while "Naga" languages such as Poumai, Mao, Maram, Rongmei (Kabui) and Tangkul, and Kuki-Chin languages such as Thadou-Kuki, Mizo, Hmar, Simte and Paite predominate in individual hill areas of the state.