The Druk Desi (Dzongkha: འབྲུག་སྡེ་སྲིད་; Wylie: 'brug sde-srid; also called "Deb Raja") was the title of the secular (administrative) rulers of Bhutan under the dual system of government between the seventeenth and nineteenth centuries. Under this system, government authority was divided among secular and religious administrations, both unified under a single leader. Druk, meaning "thunder dragon", refers symbolically to Bhutan, whose most ancient name is Druk-yul. Desi, meaning "regent", was the chief secular office in realms under this system of government.
In Bhutan, the office of Druk Desi was established by the Zhabdrung Rinpoche, Ngawang Namgyal in the 17th century under the dual system of government. Having fled sectarian persecution in Tibet, Ngawang Namgyal established the Drukpa Lineage as the state religion. Under the Bhutanese system, the powers of the government were split between the religious branch headed by the Je Khenpo of the Drukpa Lineage and the civil administrative branch headed by the Druk Desi. Both the Je Khenpo and Druk Desi were under the nominal authority of the Zhabdrung Rinpoche, a reincarnation of Ngawang Namgyal.
The Druk Desi was either a monk or a member of the laity—by the nineteenth century, usually the latter; he was elected for a three-year term, initially by a monastic council and later by the State Council (Lhengye Tshokdu). The State Council was a central administrative organ that included regional rulers, the Zhabdrung's chamberlains, and the Druk Desi. In time, the Druk Desi came under the political control of the State Council's most powerful faction of regional administrators. The Zhabdrung was the head of state and the ultimate authority in religious and civil matters.
The seat of central government was at Thimphu, the site of a thirteenth-century dzong, in the spring, summer, and fall. The winter capital was at Punakha, a dzong established northeast of Thimphu in 1527. The kingdom was divided into three regions (east, central, and west), each with an appointed penlop (governor), holding a seat in a major dzong. Districts were headed by dzongpens (district officers), who had their headquarters in lesser dzongs. The penlops were a combination of tax collectors, judges, military commanders, and procurement agents for the central government. Their major revenues came from the trade between Tibet and India and from land taxes.