Though Bhutan is a small country you will amaze to see there are more than 20 languages. It's because of the harsh geographic condition that made people stay in isolation.
Dzongkha is the name given to the language spoken in the western region and it's also known as Ngalong Kha. This Ngalong kha is used as the official language for administrative and also for the monastic centers. And usually, this administration and monastic institutions are located inside the Dzongs (Fortress), so the Ngalong Kha came to be known as Dzongkha, the language of Dzong.
Dzongkha became popular only in the second half of the 20th century only after adopting it as a national language in the 1960s.
Greetings- Ku zu Zang Po la
Thank You- Ka Drin che la
Welcome- Joen Ba Lay so
Congratulations- Tashi Delek
How are you?- Chey Ga dey bay yey?
Ending with la to word or sentence shows the respect like, Ka or Krab in Thai, and Ji in Hindi.
This is the language spoken by the people of the east. Since the eastern side is densely populated we do have a good number of people who speak this language. Today the Tsangla Kha speakers are living in all the towns across Bhutan, this language is widely spoken in other parts of Bhutan. And it is also one of the languages used in radio stations and the music industry.
And the interesting thing about this language is, it's spoken in some parts of Arunachal Pradesh in India and the Southern part of Tibet too.
The other languages such as Bumthap Kha, Khenkha, Kurtop, Dzalakha, Jyokha, Dakpakha, etc are spoken in a different parts of the country with less number of people that speaks.