Bhutan is historically known by many names. The earliest prehistoric name was Lhomon (literally, southern land of darkness) or Monyul (dark land, a reference to the Monpa aboriginal peoples of Bhutan), possibly a part of Tibet that was then beyond the pale of Buddhist teachings. Monyul was thought to have existed between 500 B.C. and A.D. 600. Later it also came to be known as Lhomon Tsendenjong (southern Mon sandalwood country) and Lhomon Khashi (southern Mon country of four approaches), found in ancient Bhutanese and Tibetan chronicles,which may also have credence and have been used by some Bhutanese scholars when referring to their homeland.
Each name has its origin. Monyul was given because Bhutan was considered land of darkness. Bhutan was land of darkness as people used to practice Bon. The Buddhist considered Bon as religion of uncivilized where animals were killed and nature was worshipped. Bhutan was called Tshendhen Jong because Tibetan believed that Bhutan was land of cypress which has great religious significance. Later, Bhutan was called Menjong Tshendhen Jong because country has not only sandalwood but full of medicinal herbs. Tibetans had to come to take herbs from Bhutan for producing medicine. Southern Land of Four Approaches or Lhomon Khazhi was named since there were four passes for Bhutanese traders and traders from outside. Four Passes/Approaches are Dungsam Kha, Pagsam Kha, Tagtserkha and Dalingkha covering four directions of Bhutan's geographical terrains.
However, the Bhutan is generally identified with two names Drukyel (Land of Thunder Dragon) and Bhutan. Native people of Bhutan don’t call Bhutan a Bhutan. They called it Drukyel, ‘Land of Thunder Dragon.’ People called themselves Drukpa (people of Druk). It is imperative to know why Bhutan is called Bhutan by outsiders and why is it called Drukyuel by native.The choice of Druk among other names for the country has a historical basis dating back to 1189.
Jetsen Milarepa(1052-1135), a famous accomplished Buddhist yogi founded the Kagyud school of Buddhism. Kagyud could roughly mean oral transmission of study. He was epitomic student of famous translator layman Marpa ((1012-1096). After that Kagyud was branched later into four different sects of ‘Kagyued’ from his disciple Gampopa namely; Barom Kagyu, Tsalpa Kagyu, Karma (or Kamtsang) Kagyu, and Phagdru Kagyu.
One of Gampopa’s principle disciples was Phagmodrupa, (1110-1170.) From Phagmodrupa and his disciples came the eight younger Kagyu schools: Drikung Kagyu, Taklung Kagyu, Drukpa Kagyu, Trophu Kagyu, Yelpa Kagyu, Martsang Kagyu, Shuksep Kagyu and Yasang Kagyu.
‘Tsangpa Gyare Yeshey Dorji, the founder of the Drukpa Kagye School was at Phoankar, Ü, Tibet, when he once saw the Namgyiphu valley hallowed with rainbow and light. Considering the sight to be auspicious for constructing a monastery, he went there to choose a site. It was then that a dragon thundered, resonating thrice in the clear winter sky. Tsangpa Gyare predicted that his teachings would flourish to the extent the thunder was heard. The monastery he built in 1189 was named Druk Sewa Jangchubling, popularly known as Druk Ralung. His teachings and the school came to be known as Druk.’ (The Origin and Description of The National Flag and National Anthem of The Kingdom of Bhutan by Dorji Penjore and Sonam Kinga).
Later Drukpa Kayud evolved into three branches known as the Toed Druk, Med Druk and Bar Druk. The first two were founded by Tsangpa Gyare's closest disciples but third one was founded by spiritual heir and nephew Önrey Dharma Sengye. Later this three got merged again and thus came the Drukpa Kagyud sect of religion.
Drukpa Kagyud was brought to Bhutan by Phajo Drugom Zhigpo(1184-1251) also known as Tobdhen Phajo in Bhutan. He was disciple of Önrey Dharma Sengye. According to hagiography, Tsangpa Gyare on his deathbed prophesied about Phajo and told his nephew to send Phajo to south to spread teachings of Buddha into Moenyuel (Land of Darkness as Bhutan was called).
Phajo propagated the Drukpa Kagyud, teachings to western Bhutan later aided by his numerous sons. In 1616, when Zhabdrung left Tibet, he was welcomed by Drukpa lamas and descendents of Phajo Drugom Zhigpo. Drukpa Kagyud became popular under reign of Zhabdrung when he unified Bhutan. Thus Bhutan is known as Druk (Land of Thunder Dragon or land of Drukpa Religion) and its inhabitants came to be known as Drukpas.)
To the outside world, Druk is known by name Bhutan. While Druk got its name because of religion from the north, Bhutan got its name due to geographical landscape from the southern neighbour. Variations of the Sanskrit words Bhota-ant (end of Bhot, an Indian name for Tibet) or Bhu-uttan (meaning highlands) have been suggested by historians as origins of the name Bhutan, which came into common foreign use in the late nineteenth century and is used in Bhutan only in English-language official correspondence.
The Drukyul or Land of Drukpa is considered one of the holiest lands in the world by Mahayanist Buddhist. It is also considered sacred land blessed by Guru Rinpoche and many Arhats from India and many saints from Tibet. It is only kingdom where Drukpa Kagud religion is practiced predominantly though other sects and religions were also respected and now empowered by constitution under Article 7 (4) which says, ‘A Bhutanese citizen shall have the right to freedom of thought, conscience and religion. No person shall be compelled to belong to another faith by means of coercion or inducement.’’
This holy land of Druk became kingdom in 17 December 1907 with enthronement of Sir Ugyen Wangchuk as First hereditary monarch of Bhutan with signing and sealing of Oath of Allegiance in Punakha Dzong by Lhengye Zhungtshog( cabinet), Central Monk Body, the Penlops, Dzongpoens and other government officials.
Today, Bhutan is called Druk not because of Thunder Dragon. It is called druk because of Drukpa Religion that is state religion enshrined in constitution as well religion followed by majority. Je Khenpo, the abbot of Bhutan is final authority in Bar Druk (Middle Drukpa) Kagyued and representative of Palden Drukpa Rinpoche, the Great Zhabdrung Ngawang Namgyel.