The article is devoted to the famous historian I.V. Yerofeyeva’s theoretical and methodological principles and historical views in the study of the epistolary heritage of the ruling elite of the Kazakh society of the 17th-19th centuries. From 1999 to 2011, there were studied and introduced into scientific circulation Kazakh khans’ and sultans’ letters based on materials from 12 largest archives and libraries of the Russian Federation, Kazakhstan and Uzbekistan by Irina Viktorovna, together with archivist B.T. Zhanaev. As a result of the scientific work carried out in 2014, at the «Abdi Company» publishing house published a two-volume fundamental study "Epistolary heritage of the Kazakh ruling elite of 1675-1821". This is a special collection of historical documents, where the author of the project, introduction, Khans’ biographies, scientific comments, compiler and responsible editor was I.V. Yerofeyeva. The collection includes 26 Kazakh khans’ and sultans’ 811 letters, chronologically covering the period from 1675 to 1821.
It should be noted that the beginning of the mass identification and publication of these historical documents was laid in the Soviet period, but it became more intense after the declaration of independence of Kazakhstan. The article attempts to show I.V. Yerofeyeva’s role in this process, her positions and concepts reflected in the disclosure of the significance of the epistolary heritage for historical science.