Dzongkha or Bhutanese (རྫོང་ཁ་ [dzoŋ'kʰa]), is a Sino-Tibetan language spoken by over half a million people in Bhutan, it is the sole official and national language of the Kingdom of Bhutan. The Tibetan alphabet is used to write Dzongkha. The word dzongkha means, "the language of the fortresses", where kha is language and dzong is "fortresses"—the fortress-like dzong architecture characterises monasteries established throughout Bhutan by its unifier, Ngawang Namgyal, 1st Zhabdrung Rinpoche, in the 17th century. As of 2013, Dzongkha had 171,080 native speakers and about 640,000 total speakers.