The International Refugee Organization (IRO) was founded on April 20, 1946 to deal with the massive refugee problem created by World War II. A Preparatory Commission began operations fourteen months previously. It was a United Nations specialized agency and took over many of the functions of the earlier United Nations Relief and Rehabilitation Administration. In 1952, its operations ceased, and it was replaced by the Office of the United Nations High Commissioner for Refugees (UNHCR).

The Constitution of the International Refugee Organization, adopted by the United Nations General Assembly on December 15, 1946, specified the agency's field of operations. Controversially, this defined "persons of German ethnic origin" who had been expelled, or were to be expelled from their countries of birth into the postwar Germany, as individuals who would "not be the concern of the Organization." This excluded from its purview a group that exceeded in number all the other European displaced persons put together. Also, because of disagreements between the Western allies and the Soviet Union, the IRO only worked in areas controlled by Western armies of occupation.

The Bhutanese refugees are people claiming to be Lhotshampas ("southerners"), a group of people of Nepalese origin, including some Kirat, Tamang, and Gurung peoples. These refugees registered in refugee camps in eastern Nepal during the 1990s affirming to be Bhutanese citizens deported from Bhutan. As Nepal and Bhutan have yet to implement any agreement on repatriation, many Bhutanese refugees have since resettled to North America and Europe under the auspices of the Office of the United Nations High Commissioner for Refugees.

The earliest surviving records of Bhutan's history show that Tibetan influence already existed from the 6th century. King Songtsen Gampo, who ruled Tibet from the years 627 to 649, was responsible for the construction of Bhutan's oldest surviving Buddhist temples, the Kyichu Lhakhang in Paro and the Jambay Lhakhang in Bumthang. Settlement in Bhutan by people of Tibetan origin happened by this time.

The first reports of people of Nepalese origin in Bhutan was around 1620, when Shabdrung Ngawang Namgyal commissioned a few Newar craftsmen from the Kathmandu valley in Nepal to make a silver stupa to contain the ashes of his father Tempa Nima.