In the very beginning when Buddhism had still not spread in Tibet, the state was protected by the three cults of Bon, Deu, and Drung. This country was very closed to neighboring Tibet where some of the kings of the royal dynasty supported the followers of Bon. Other members of the dynasty, however, exile the Bon teachers beyond the borders and propagated Buddhism. As a consequence, some of the Bonpas wandered beyond the frontiers and established themselves here in southern region gradually spreading the Bon practices, in which the deities of the Sky and Earth and the various worldly and cosmic god and goddesses such as those of fire, wind, sun, and moon are worshipped. Because of this they were deprived of the enlightenment of the Teaching of Lord Buddha and, not comprehending the principles of action and retribution and of merit and sin, it was as if they resided in a pit of darkness (mun). Therefore the country was called Mon and the inhabitants Monpa. Joining the two terms Lho (south) and Mon (a corruption of term for darkness), the etymology of Lho Mon would appear to be appropriate.
Various other theories regarding the origin of the name Bhutan exist. (i) That it is derived from the Sanskrit Bhota ant, meaning that country’s geographical situation at the end of Bhot (Tibet). The plausible explanation of this theory is that Bhutan is geographically and politically a separate country. (ii) the second derivative regarding the origin of the word Bhutan is said to be from Bhu-uttan or Highland. This is also plausible because of the great elevation at which the country lies. (iii) Another theory is that the word Bhutan is a corruption of the word Bhotstan i.e., Bhotas or the Tibetans who seem to have migrated there. This theory appears to be unlikely, because, even Tibet was not known in ancient times as Bhota but Ta Fung which later became Tibet.