Djongkha

Japanese: Dzongkha

...the classification name and main distribution area are: (1) Central dialect (U-tsang, named after the U-tsang region centered around Lhasa and the Gtsang region centered around Shigatse) (2) Southeastern dialects (also called the Khams dialect): Naqu and Changdu areas of the Tibet Autonomous Region, Ganzi and Ataba Tibetan (Zo) Autonomous Prefecture in Sichuan Province, Diqing Tibetan (Zo) Autonomous Prefecture in Yunnan Province, and Yushu Tibetan (Zo) Autonomous Prefecture in Qinghai Province; (3) Northeastern dialects (also called the Amdo dialect): Qinghai Province, Gannan Tibetan (Zo) Autonomous Prefecture and Tianzhu Tibetan (Zo) Autonomous County in Gansu Province, and Ganzi and Ataba Tibetan (Zo) Autonomous Prefecture in Sichuan Province; (4) Western dialects: In addition to the Balti dialect mentioned above, Ladakh region of the Kashmir region of India and Himachal Pradesh; (5) Southern dialects: Himachal Pradesh, Uttar Pradesh, Nepal, Sikkim, and Bhutan. The Sherpa language of Nepal and Dzongkha, the national language of Bhutan, are included in the southern dialects. It belongs to the Tibeto-Burman branch of the Sino-Tibetan language family, and is thought to form a subgroup of Tibetan languages together with the Himalayan languages of Nepal, the Gyaron language of Sichuan Province, and the Qiang language of Sichuan Province, but there are various theories about the genealogical relationship with the languages within the group.

From Bhutan

…They practice Hinduism or Buddhism and make up about 30% of the population. The official language is Dzongkha, a southern dialect of Tibetan spoken in the capital and surrounding areas, but it has no orthography and uses the Tibetan alphabet.
[history]
Its history before the 8th century is unclear, but according to legend, Buddhism spread from India in the mid-8th century.

*Some of the terminology explanations that mention "Dzongkha" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…分類名とおもな分布地域は，(1)中央部方言(ラサを中心とするウュ(衛)dbus地方，シガツェを中心とするツァン(蔵)gtsang地方の名をとってウーツァンdbus gtsang方言ともいう)：チベット自治区，(2)東南部方言(カム(康)khams方言ともいう)：チベット自治区那曲･昌都地区，四川省甘孜･阿壩チベット(蔵)族自治州，雲南省迪慶チベット(蔵)族自治州，青海省玉樹チベット(蔵)族自治州，(3)東北部方言(アムド(安多)amdo方言ともいう)：青海省，甘粛省甘南チベット(蔵)族自治州･天祝チベット(蔵)族自治県，四川省甘孜･阿壩チベット(蔵)族自治州，(4)西部方言：先のバルティー語のほかは，インドのカシミール地区ラダック地方，ヒマーチャル･プラデーシュ，(5)南部方言：ヒマーチャル･プラデーシュ，ウッタル･プラデーシュ，ネパール，シッキム，ブータン。ネパールのシェルパSherpa語，ブータンの国語ゾンカDzongkha語などは南部方言に含まれる。　系統的には，シナ･チベット語族のチベット･ビルマ語派に属し，ネパールに分布するヒマラヤ諸語，四川省に分布するギャロン(嘉戎)語，チャン(羌)語などとともに，その下位語群，チベット語群を形成すると考えられるが，語群内諸言語との系譜関係についても諸説がある。…