How is Dzongkha related to the Tibetan language?

Dzongkha is the national and official language of Bhutan and is classified as a dialect of the Tibetan language.12

As part of the Tibeto-Burman group within the Sino-Tibetan language family, the Tibetan language is categorized into four dialect groups: Central, Northern, Western, and Southern. Dzongkha falls under the Southern group, which is primarily found in Bhutan, Sikkim, and Nepal. Like other forms of Tibetan, it utilizes a script derived from the Gupta script, which itself evolved from the northern form of the ancient Indian Brahmi writing system.13