During the Zhivkov era, Bulgaria signed several friendship treaties with other Comecon nations to ease the exchange of workers. In the 1980s, for example, a large number of Bulgarians worked in the construction and timber industries of the Komi Autonomous Soviet Socialist Republic (Komi ASSR) under an exchange agreement with the Soviet Union. Workers were expected to return to their own countries when their contracts ended, but they did not always do so. For example, some Vietnamese construction workers sent to Bulgaria under Comecon agreement in the 1980s remained, and in 1991 the Vietnamese population of Bulgaria was 11,000. Because they arrived completely unprepared for life in Bulgaria and began working after only one month of training and language courses, the Vietnamese who remained in Bulgaria generally received the hardest and lowest-paying jobs and often became involved in criminal activity. In 1991 several violent incidents involving Vietnamese provoked calls for their repatriation. In response, the government made plans to expel all resident Vietnamese from Bulgaria in 1992.

Data as of June 1992