“Kitab-i dedem Korkut” is the only surviving monument of the written epic among the Turkic Oghuz peoples. Until recently, two undated manuscripts of “Kitab-i dedem Korkut” were known – the so-called Dresden and Vatican manuscripts (both, according to paleographic data, relate to the end of the 16th century). The first was discovered in the Dresden library by G. Dietz in 1815; the second one was found in the Vatican Library, translated and published by E. Rossi in 1950. In 2018, a new manuscript which is referred to as the “Book of Dede Korkut” was found in Iran in the private collection (“The Gonbad manuscript”); its brief (mostly linguistical) research, along with a facsimile of the manuscript, was published by the collective of authors in June 2019. This copy dates back to the 2nd half of the 18th century and comes from the Northeastern Iran. Text of the manuscript (on 31 folios) it consists of 25 parts, which contains some genealogies and tells about the exploits of Kazan (one of the central and ancient characters of the “Book of Dede Korkut” according to previously known manuscripts); other heroes of this epic are also mentioned, including Korkut himself. The events referred to in the text take place in the territories of Transcaucasia, which are located much to the east of those referred to in the previously known manuscripts. The date of this source to the 18th century (even if we have a relatively late imitation of the epic) indicates, first of all, a certain actualization of the Turkic cultural heritage in Iran.