On the basis of the analysis of sources of personal origin — letters of the Soviet ballet director Y.E. Brunak — the problem of the formation of the national ballet in Vietnam is highlighted. Letters from Vietnam to the ballet master Y.A. Bakhrushin have the character of personal messages and contain information about the initial stage of activity of the Vietnamese School of Dance, the creation of an experimental choreographic studio and its first tours. Special attention is paid to the characterization of the personality of the author and addressee of the letters, their education and professional affiliation, personal attitude to the events described. The aim of the article is to introduce primary sources and facts revealed on their basis concerning the creative biography of Y.E. Brunak, her role in the formation of professional choreographic art in Vietnam. A comparative analysis of the information contained in the texts of Y.E. Brunak’s letters with information about the same events from the memoirs of N.P. Karachentsov, Y.A. Bakhrushin, H.F. Mustaev, Wu viet kuong, Truong Le Zap, etc. has been carried out. The conclusion is made about the significant contribution of Soviet teachers to the formation of Vietnamese national ballet in the 1950—1960s. This contribution was expressed in participation in the creation of a national choreographic school based on the system of Russian choreographic education, in the introduction of the methodology of teaching classical dance according to the Russian school, in the transfer of a number of Soviet productions to the Vietnamese ballet stage, in the formation of the repertoire policy of the Vietnamese ballet theatre. The activities of Russian choreographers played a significant role in the institutionalization of Vietnamese ballet. The epistolary heritage of Y.E. Brunak allows us to see the essential aspects of this process.